Apparatus for carrying out electrochemiluminescence test measurements

ABSTRACT

Apparatus for the conduct of electrochemiluminescence measurements includes an ECL chamber having a transparent window defining one wall of the chamber and a photodetector mounted closely adjacent thereto. An assay fluid is subject to a magnetic field and is electrically energized. Electrochemiluminescence induced in the fluid is measured by the photodetector.

This is a Divisional of application Ser. No. 09/076,325, filed May 11,1998, now U.S. Pat. No. 6,200,531; and said application is herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This application relates generally to apparatus and methods fordetecting and measuring analytes of interest by inducingelectrochemiluminescence (ECL) in a test sample and detecting theresulting light.

Numerous methods and systems have been developed for detecting andquantitating analytes of interest in chemical, biochemical, biological,and environmental samples. Methods and systems that are capable ofmeasuring toxins, environmental contaminants, pharmacological agents,bioactive substances, metabolites, pathogenic organisms, proteins andnucleic acids are of substantial value to researchers and clinicians. Atthis time, there are a number of commercially available instruments thatutilize ECL for analytical measurements. These instruments havedemonstrated exceptional performance.

The high cost, complex engineering and long development time required tocustom-design and manufacture ECL instruments have delayed broadimplementation of ECL technology. Clearly, there remains a need for ECLsubsystems or modules that can be easily adapted to a broad variety ofdifferent applications.

Current needs for precision analytical testing instrumentation areextraordinarily diverse. For example, pharmaceutical screening analysesrequire instruments that can perform large numbers of analyses at veryhigh speeds on very small quantities of sample. In addition, suchinstruments may need to perform many different types of highly sensitivequantitative tests utilizing different detection methods. Similarly,clinical diagnostic analyses for human health care typically requirehighly sensitive and exceptionally reliable instrumentation. Incontrast, it is expected that commercial instruments intended for fielduse would be small, perhaps portable, simple to use, and operable withonly limited power. Low production and maintenance costs are oftenpredominant considerations.

2. Description of the Prior Art

An apparatus for carrying out electrochemiluminescence test measurementsis found in U.S. Pat. No. 5,466,416 assigned to IGEN, Inc. Across-sectional view of a flow cell is depicted in FIG. 1. Flow cell 18comprises a removable plug 20, a gasket 22, a retainer block 24, acounter electrode 26, an ECL test chamber 28, a working electrode 30, atransparent block 32, a counter electrode 34, a retainer block 36, aconduit 46, a main housing 48, a chamber 40, a lateral block 42, a frit44, a gasket 50, a plug 52, an O-ring seal 56, a threaded coupling 58, aconduit 60, a pivot arm 61, a magnet 62, and a threaded coupling 64.

Flow cell 18 includes a main housing 48 formed of a durable, transparentand chemically inert material such as acrylic or polymethylmethacrylate. Threaded coupling 64 defines a fluid inlet in a lowersurface of housing 48 and is contiguous with conduit 46. Conduit 46extends through housing 48 from coupling 64 to an upper surface ofhousing 48. Threaded coupling 58 defines a fluid outlet in a lowersurface of housing 48 and is contiguous with conduit 60. Conduit 60extends through housing 48 from coupling 58 to the upper surface ofhousing 48. ECL test chamber 28 is bounded by the upper surface ofhousing 48, a lower surface of block 32, lower and side surfaces ofcounter electrodes 26 and 34, the upper surface of working electrode 30,and the interior surface of gasket 22. Chamber 28 communicates with bothconduit 60 and conduit 46. Fluid introduced through coupling 64 maytravel through conduit 46 to chamber 28 and exit through conduit 60 andcoupling 58.

Working electrode 30, counter electrode 26, and counter electrode 34 mayconsist of electrically-conductive materials such as platinum or gold.Working electrode 30 has a generally flat, elongate, rectangular shapehaving a longitudinal axis arranged generally transverse to alongitudinal axis of chamber 28. Electrode 30 is positioned centrallybetween conduits 60 and 46 in a shallow groove formed in the uppersurface of housing 48. An adhesive (not shown) bonds electrode 30 to thegroove in housing 48. Accordingly, at least three seams betweenelectrode 30 and housing 48 abut chamber 28; one on each latitudinalside of electrode 30 and a third at a longitudinal end of electrode 30.As displayed in FIG. 1, electrode 30 is approximately as wide as the gapbetween counter electrodes 26 and 34 and is positioned centrallytherebetween.

Counter electrodes 26 and 34 have an “L”-shaped cross-section, theshorter arm having a length slightly longer than the thickness of block32 and the longer arm having a length of less than half of the width ofblock 32. The two arms of each electrode are flat, thin and positionedperpendicular to each other but in different planes. The widths ofelectrodes 26 and 34 are approximately less than half of the thicknessof block 32. Counter electrode 26 is affixed to a side of transparentblock 32 and is held in place by retainer block 24. On the opposite sideof transparent block 32, counter electrode 34 is similarly affixed byretainer block 36.

Magnet 62 is affixed to pivot arm 61. In its raised position, pivot arm61 positions magnet 62 beneath working electrode 30, sandwiching asegment of housing 48 therebetween. In its lowered position, pivot arm61 pivots down and away from housing 48 thereby significantly increasingthe distance between working electrode 30 and magnet 62.

A reference electrode assembly, integrated into housing 48, compriseschamber 40, block 42, gasket 50, frit 44, plug 52, and gasket 56. Anionic fluid (not shown) is retained within chamber 40. Chamber 40comprises a cavity defined by housing 48, gasket 50 and block 42. Frit44 extends into conduit 60 and is sealed by O-ring 56 and plug 52.toprevent fluidic interchange.

A refill aperture (not shown) is provided in housing 48 to allowreplacement of the ionic fluid held in chamber 40. The refill apertureis sealed by removable plug 20. To achieve useful and reproducible ECLtest measurements, flow cell 18 utilized a temperature-controlledenvironment. FIG. 2 illustrates an apparatus 80 from U.S. Pat. No.5,466,416 for providing a temperature-controlled environment for flowcell 18. Apparatus 80 comprises a photomultiplier tube (PMT) 82, aninsulating cover 92, a housing 94, a plurality of foil heaters 96, acircuit board 84, flow cell 18, a magnet 62, a pivot arm 61, a linearactuator 98, a coil spring 102, an air space 90, and a fan 104. Forreference purposes, housing 48, block 42, retainer block 24, counterelectrode 26, and block 32 are specifically labelled on flow cell 18.

Foil heaters 96 are positioned on the outer lateral surfaces and theouter lower surface of housing 94. The upper surface of housing 94adjacent PMT 82 is formed of a transparent material while the remainingportions of housing 94 are preferable opaque. Insulating cover 92 coversfoil heaters 96 as well as the remaining uncovered outer surfaces ofhousing 94 to provide thermal insulation and prevent the entry of lightinto flow cell 18. PMT 82 is a conventional photomultiplier tube mountedon the upper surface of housing 94. PMT 82 is physically large comparedto the size of the flow cell, requires a high-voltage power supply, andis highly sensitive to the surrounding temperature and the presence ofmagnetic fields. It is preferable that PMT 82 be maintained at arelatively low temperature. Flow cell 18 is positioned below PMT 82inside temperature-controlled housing 94.

Circuit board 84, incorporating operating electronics for apparatus 80,is mounted on an interior surface of housing 94 adjacent flow cell 18.As shown, linear actuator 98 is connected to coil spring 102 which, inturn, is connected to pivot arm 61. Magnet 62 is affixed to an end ofpivot arm 61.

The temperature within housing 94 is controlled through the operation offoil heaters 96 in conjunction with fan 104. Fan 104, affixed to theinterior surface of housing 94, circulates air within air space 90. Airspace 90 extends throughout the interior of housing 94 and surroundseach component therein, including, specifically, flow cell 18. Air space90 further includes an air gap between the upper surface of flow cell18, e.g., block 32, and the upper interior surface of housing 94.

As described above, pivot arm 61, shown in its lowered position, canpivot upward to place magnet 62 within housing 48 of flow cell 18.Linear actuator 98, operating in conjunction with coil spring 102,causes pivot arm 61 to move.

In an ordinary operation, magnet 62 is raised into a position adjacentto working electrode 30 of flow cell 18 to attract magnetic particles inan assay fluid in chamber 28 to the vicinity of working electrode 30.Shortly thereafter, to avoid magnetic interference with the operation ofPMT 82, magnet 62 is withdrawn from flow cell 18 prior to the inductionof electrochemiluminescence in the assay sample fluid. Conventionally,magnet 62 is not positioned to collect magnetic particles during theapplication of electrical energy to the assay fluid. Magnet 62 isusually retracted before electrochemiluminescence is induced to avoidmagnetic interference with ECL measurements by PMT 82. Removal of themagnetic field from working electrode 30 may allow a flowing-assaysample fluid to carry away magnetic particles collected there.

Methods of calibration for apparatus 80 convolve diagnosis of theeffectiveness of bead capture and the effectiveness of the ECL cell.Therefore, calibration is preferably achieved using bead-based standards(e.g. magnetic beads coated with ECL labels).

As shown, apparatus 80 includes thermal insulation between PMT 82 andflow cell 18. PMT 82 is very temperature-sensitive in that heatincreases the background noise signal generated by PMT 82. Typically,PMT 82 is maintained in a moderate to low temperature environment. Sincethe ECL process generates considerable heat, flow cell 18 is thermallyisolated from PMT 82. The use of thermal insulating material betweenflow cell 18 and PMT 82 increases the length of the optical path fromworking electrode 30 to PMT 82 and, therefore, reduces the efficiencywith which light emitted at working electrode 30 is transmitted to PMT82.

Additionally, it should be readily apparent that the optical pathbetween chamber 28 of flow cell 18 and PMT 82 includes multipleair-solid and solid-solid boundaries. These transitions between mediareduce the amount of ECL-generated light which ultimately reaches PMT82. Light generated between counter electrode 26 and working electrode30 or between counter electrode 34 and working electrode 30 passes fromthe assay fluid in chamber 28 through a bottom surface of block 32,through the bulk of block 32 and through the upper surface of block 32.At the lower surface of block 32, light is reflected back towardshousing 48 and, in particular, working electrode 30. Light travellingthrough the bulk of block 32 is diffused and may be gradually separatedinto component wavelengths. At the upper surface of block 32, a portionof the incident light is internally reflected back into the bulk ofblock 32 while the remainder is transmitted into air space 90.Additionally, at the boundary between block 32 and air space 90, thelight rays will be bent away from PMT 82 due to the decrease inrefractive index across the boundary. Consequently, the amount of lightdirected towards PMT 82 is reduced.

The light travels through air space 90 to the lower surface of housing94 where, again, some light is reflected back towards flow cell 18 whilethe remainder is transmitted into the bulk of housing 94. Within thebulk of housing 94, the light is diffused and may be further caused toseparate into component wavelengths. At the upper surface of housing 94,where PMT 82 abuts housing 94, a portion of the light is internallyreflected into the bulk of housing 94 while a remainder portion istransmitted to PMT 82. The aforedescribed diffusion, bending, andreflection of light may significantly reduce the amount of ECL-generatedlight which is actually incident upon PMT 82.

As shown, flow cell 18 includes electrode-housing seams within ECLchamber 28. The adhesive present at these seams and used to affixworking electrode 30 to housing 48 may deteriorate and erode over time.As a result, assay fluid components, cleaning fluid components, or othermaterials may collect in the seams between electrode 30 and housing 48.The collected materials may react with or otherwise contaminatecomponents of subsequent assays and thereby affect assay results.

OBJECTS OF THE INVENTION

It is, therefore, a primary object of the present invention to provideapparatus and methodology for carrying out improvedelectrochemiluminescence test measurements.

A further object of the invention is to provide apparatus andmethodology for the efficient detection of light generated during anelectrochemiluminescence assay.

Still a further and related object of the invention is to provide amodular ECL measurement apparatus for rapid and efficient incorporationinto an application-specific diagnostic device.

Another object of the invention is to provide apparatus and methodologyfor conducting electrochemiluminescence test measurements underconditions of continuous fluid flow upon an assay sample containingmagnetic particles.

A still further object of the invention is to provide apparatus andmethodology for applying a magnetic field to assay materials during theinduction of electrochemiluminescence and simultaneously detecting thelight generated thereby.

Another object of the invention is to provide apparatus that integrateseach of the components needed to perform an ECL measurement in a singleopen-architecture ECL module.

Yet another object of the invention is to provide a modular apparatusfor carrying out an ECL measurement that comprises a modular systeminterface.

A further object of the invention is to provide apparatus andmethodology for an integrated system for assaying one or more samplesfor one or more analytes of interest.

A related object of the invention is to provide apparatus for conductingmultiple simultaneous or near-simultaneous ECL measurements and forsharing an assay sample sampling device, a power supply, a controller, asystem interface, and a user interface.

An additional object of the invention is to provide apparatus andmethodology for normalizing the operations of two or more ECL modules.

Another object of the invention is to provide an apparatus for ECLmeasurements that comprises a modular system interface that is adaptedfor convenient coupling to other analytical or processing devices.

Another object of the invention is to provide apparatus and systemscapable of detecting analytes in a sample by means ofelectrochemiluminescence and one or more other analytical techniques.

Still another object of the invention is to provide an integrated systemfor processing samples, amplifying nucleic acids, and measuring nucleicacids.

SUMMARY OF THE INVENTION

These and other objects of the invention are achieved in an apparatusfor the conduct of electrochemiluminescence measurements which includesa cell having at least one cell wall which includes a transparentportion adjacent to an ECL chamber defined within the cell, a workingelectrode abutting the ECL chamber and in optical registration with thetransparent portion, a counter electrode abutting the ECL chamber and anelectrically-shielded window adjacent to and in optical registrationwith the transparent portion of the cell wall.

The apparatus of the invention may also include a photodetector, e.g. aphotodiode, in optical registration with the electrically-shieldedwindow, the transparent portion of the cell wall and the workingelectrode.

In preferred embodiments of the invention, the working electrode isremovably fitted within the cell and has a planar electrode surfaceabutting the ECL chamber such that no seam is created between theworking electrode and the ECL chamber. A removable magnet is providedfor applying a magnetic field to the working electrode.

The object of creating an integrated system for assaying a sample orplurality of samples for a plurality of analytes of interest is alsoachieved in systems comprising a plurality of modules which may share acommon sample handling subsystem, a common power supply, a commoncontroller and/or a common system or user interface.

According to an aspect of the present invention an apparatus for theconduct of electrochemiluminescence measurements includes a cell havingat least one cell wall which includes a transparent portion adjacent toan ECL chamber defined within the cell, a working electrode abutting theECL chamber and in optical registration with the transparent portion, acounter electrode abutting the ECL chamber, and an electrically-shieldedwindow adjacent to and in optical registration with the transparentportion.

According to another aspect of the present invention an apparatus forthe conduct of electrochemiluminescence measurements includes a cellhaving at least one cell wall which includes a transparent portionadjacent to an ECL chamber defined within the cell, a working electrodeabutting the ECL chamber and in optical registration with thetransparent portion, a counter electrode abutting the ECL chamber, aphotodiode in optical registration with the transparent portion, and anoptical filter adjacent to and in optical registration with thetransparent portion.

According to another aspect of the present invention an apparatus forthe conduct of electrochemiluminescence measurements includes a cellhaving at least one cell wall which includes a transparent portionadjacent to an ECL chamber defined within the cell, a working electrodeabutting the ECL chamber and in optical registration with thetransparent portion, and a counter electrode abutting the ECL chamberand having an aperture in optical registration with the transparentportion.

According to still another aspect of the present invention an apparatusfor the conduct of electrochemiluminescence measurements includes a cellhaving at least one cell wall which includes a transparent portionadjacent to an ECL chamber defined within the cell, a working electrodeabutting the ECL chamber and in optical registration with thetransparent portion, and a counter electrode abutting the ECL chamber,wherein the working electrode is removably fitted within the cell andhas a planar electrode surface abutting the ECL chamber.

According to still another aspect of the present invention an apparatusfor the conduct of electrochemiluminescence measurements includes a cellhaving at least one cell wall which includes a transparent portionadjacent to an ECL chamber defined within the cell, a working electrodehaving a planar electrode surface abutting the ECL chamber and inoptical registration with the transparent portion of the cell wall, theworking electrode being positioned within the cell such that no seambetween the working electrode and the cell abuts the ECL chamber, and acounter electrode abutting the ECL chamber.

According to still another aspect of the present invention an apparatusfor the conduct of electrochemiluminescence measurements includes a cellhaving at least one cell wall which includes a transparent portionadjacent to an ECL chamber defined within the cell, a working electrodeabutting the ECL chamber and in optical registration with thetransparent portion, a counter electrode abutting the ECL chamber, aphotodiode adjacent to and in optical registration with the transparentportion, and a magnetic field generating device operable to apply amagnetic field at the working electrode.

According to yet another aspect of the present invention an apparatusfor the conduct of electrochemiluminescence measurements includes a cellhaving at least one cell wall which includes a transparent portionadjacent to an ECL chamber defined within the cell, a working electrodeabutting the ECL chamber and in optical registration with thetransparent portion, a counter electrode abutting the ECL chamber, and aphotodiode adjacent to and in optical registration with the transparentportion, the photodiode having a detection sensitivity substantiallylimited to light having a wavelength in a range of 400 nm to 900 nm.

According to yet another aspect of the present invention an apparatusfor the conduct of electrochemiluminescence measurements includes a cellhaving at least one cell wall which includes a transparent portionadjacent to an ECL chamber defined within the cell, a working electrodeabutting the ECL chamber and in optical registration with thetransparent portion, a counter electrode abutting the ECL chamber andhaving an aperture in optical registration with the transparent portion,a photodetector adjacent to and in optical registration with thetransparent portion, and a magnetic field generating device, inregistration with the aperture, operable to apply a magnetic field tothe working electrode.

According to another aspect of the present invention an apparatus forthe conduct of electrochemiluminescence measurements includes a cellhaving at least one cell wall which includes a transparent portionadjacent to an ECL chamber defined within the cell, a working electrodeabutting the ECL chamber and in optical registration with thetransparent portion, a counter electrode abutting the ECL chamber, aphotodiode adjacent to and in optical registration with the transparentportion, a magnetic field generating device operable to apply a magneticfield to the working electrode, and a magnetic field detector, inregistration with the magnet device.

According to another aspect of the present invention an apparatus forthe conduct of electrochemiluminescence measurements includes a cellhaving at least one cell wall which includes a transparent portionadjacent to an ECL chamber defined within the cell, a working electrodeabutting the ECL chamber and in optical registration with thetransparent portion, a counter electrode abutting the ECL chamber, aphotodiode, adjacent to and in optical registration with the transparentportion, for detecting electrochemiluminescence induced in an assayfluid in the ECL chamber and for producing an ECL signal representativeof an intensity of the electrochemiluminescence, a storage device,coupled to the photodiode, in which a calibration signal representativeof a calibration electrochemiluminescence may be stored, and aprocessor, coupled to the photodiode and to the storage device, operableto calculate an intensity value as a function of the ECL signal and thecalibration signal.

According to another aspect of the present invention a cell for theconduct of electrochemiluminescence measurements includes a first basehaving a first interior surface, a planar working electrode positionedon the first interior surface, a second base having a second interiorsurface and having a transparent portion therein to allow light to passtherethrough, a planar counter electrode positioned on the secondinterior surface, the counter electrode having at least one openingtherein to allow the light to pass therethrough in registration with theworking electrode and the transparent portion of the second base, agasket positioned between the working electrode and the counterelectrode to define therebetween a cell volume, the volume communicatingwith the opening in the counter electrode, and a retaining device,coupled to the bases, wherein the interior surfaces of the bases are inopposing relationship to form the cell and wherein the second baseincludes a conduit through which fluid may be introduced into andremoved from the cell volume.

According to another aspect of the present invention a cell for theconduct of electrochemiluminescence includes cell structural elements, aworking electrode and a counter electrode, at least one of thestructural elements having a transparent portion therein, wherein theworking electrode is mounted on an interior surface of a structuralelement, a portion. of the working electrode and the transparent portionof the at least one structural element defining, at least in part, achamber for the conduct of electrochemiluminescence, the workingelectrode including the entirety of a continuous planar surface of thechamber and the portion of the working electrode and the transparentportion of the structural element being optically in registration withone another.

According to another aspect of the present invention a method forconducting an ECL measurement includes the steps of introducing an assaysample into an ECL chamber within a flow cell, simultaneously applyingan electric field and a magnetic field to the assay sample in the ECLchamber, and measuring, through an electrically-shielded window defininga wall of said ECL chamber, electrochemiluminescence induced in theassay fluid in the ECL chamber while the electric field and the magneticfield are applied.

According to another aspect of the present invention a method forconducting an ECL measurement includes the steps of introducing an assaysample into an ECL chamber within a flow cell, simultaneously applyingan electric field and a magnetic field to the assay sample in the ECLchamber, and measuring with a semiconductor photodetectorelectrochemiluminescence induced in the assay fluid in the ECL chamberwhile the electric field and the magnetic field are applied.

According to another aspect of the present invention a method fornormalizing a plurality of ECL measurement instruments includes thesteps of conducting an ECL measurement with a reference ECL measurementinstrument upon a reference sample to produce a reference ECL signal,conducting an ECL measurement with a test ECL measurement instrumentupon the reference sample to produce a test ECL signal, and calculatinga correction transform function as a function of the reference ECLsignal and the test ECL signal.

According to another aspect of the present invention an apparatus forthe conduct of assay measurements includes a cell having at least onecell wall which includes a transparent portion adjacent to an ECLchamber defined within the cell, a working electrode abutting the ECLchamber and in optical registration with the transparent portion, acounter electrode abutting the ECL chamber, a first light detector,optically coupled to the ECL chamber and in optical registration withthe transparent portion, for detecting electrochemiluminescence inducedwithin the ECL chamber, a light source, optically coupled to the ECLchamber, for providing light to the ECL chamber, and a second lightdetector, optically coupled to the ECL chamber.

According to another aspect of the present invention an assay systemincludes a plurality of ECL modules and a controller device coupled toeach of the plurality of ECL modules and operable to control anoperation of each of the plurality of ECL modules.

According to another aspect of the present invention an assay systemincludes a plurality of ECL modules and a power supply coupled to eachof the plurality of ECL modules and operable to supply electrical powerto each of the plurality of ECL modules.

According to another aspect of the present invention an assay systemincludes a plurality of ECL modules and a sample introduction devicecoupled to each of the plurality of ECL modules and operable to supply asample to each of the plurality of ECL modules.

According to another aspect of the present invention an assay systemincludes a plurality of ECL modules and a waste handling device coupledto each of the plurality of ECL modules and operable to receive wastefrom each of the plurality of ECL modules.

According to another aspect of the present invention an assay systemincludes a temperature-controlled enclosure and a plurality of ECLmodules positioned within the temperature-controlled enclosure.

According to another aspect of the present invention an assay systemincludes an ECL module having an assay fluid outlet and an assay modulehaving an assay fluid inlet coupled to the assay fluid outlet.

According to another aspect of the present invention an assay systemincludes an assay module having an assay fluid outlet and an ECL modulehaving an assay fluid inlet coupled to the assay fluid outlet.

According to another aspect of the present invention an assay systemincludes an ECL module having a first assay fluid inlet and a firstwaste fluid outlet and an assay module having a second assay fluid inletcoupled to first assay fluid inlet and having a second waste fluidoutlet coupled to the first waste fluid outlet.

According to another aspect of the present invention a modular ECL assaysubsystem adapted for connection to and use with a power supply, acontroller, and a fluid exchange system common to a plurality of themodular ECL subsystems includes a cell having at least one cell wallwhich includes a transparent portion adjacent to an ECL chamber definedwithin the cell, a working electrode abutting the ECL chamber and inoptical registration with the transparent portion, a counter electrodeabutting the ECL chamber, a light detector, optically coupled to the ECLchamber, for detecting electrochemiluminescence induced within the ECLchamber, a waveform generator coupled to at least one of the workingelectrode and the counter electrode and operable to generate an electricsignal, a subsystem controller coupled to the waveform generator andoperable to control an operation of the waveform generator, and aninterface to the cell, coupled to each of the subsystem controllers, tothe power supply, to the controller, and to the fluid exchange system,the controller being operable to control the subsystem controller, thepower supply being operable to supply electrical power to the subsystemcontroller and the fluid exchange system being operable to provide anassay fluid to the cell and to receive a waste fluid from the cell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a prior art flow cell;

FIG. 2 illustrates a prior art ECL measurement apparatus;

FIGS. 3A and 3B illustrate a flow cell according to an embodiment of thepresent invention;

FIGS. 4A, 4B, 4C, and 4D illustrate a flow cell component according toan embodiment of the present invention;

FIG. 5 illustrates an ECL measurement apparatus according to anembodiment of the present invention;

FIG. 6 is a flow chart illustrating an ECL testing method according toan embodiment of the present invention;

FIG. 7 is a block diagram of an integrated system for ECL measurementsaccording to an embodiment of the present invention;

FIGS. 8A and 8B illustrate components of an integrated system for ECLmeasurements according to an embodiment of the present invention;

FIG. 9A is a block diagram of an integrated system for ECL measurementsaccording to an embodiment of the present invention;

FIG. 9B is a block diagram of an integrated system for ECL measurementsaccording to an embodiment of the present invention;

FIGS. 10A, 10B, 10C and 10D illustrate components of an integratedsystem for ECL measurements and for measurements with other devicesaccording to an embodiment of the present invention; and

FIG. 11 illustrates a flow cell according to an embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention is in an ECL module capable of carrying out ECLmeasurements and capable of being integrated with other modules and/orinstrumentation in a modular system. Advantageously, the ECL module issmall, easy and inexpensive to manufacture, reliable and durable. TheECL module can be rapidly and efficiently incorporated into a variety ofinstruments specially-designed to serve particular markets, performparticular functions, or otherwise satisfy the requirements of specificapplications. The ECL module dramatically reduces the time and costrequired to create new ECL-based instruments.

Instruments incorporating an ECL module benefit from the standardizationinherent in the module's design. Quality control testing, calibration,service, and upgrading of an instrument based upon an ECL module aregreatly simplified since each process benefits from the interchangeablenature of the ECL module.

In the following the term transparent is defined as capable oftransmitting any amount of light. In this sense, transparent matter maypass light fully or partially or it may be translucent. The term lightrefers to any electromagnetic radiation.

Objects in optical registration have a light path between them. A lightpath may include optical elements such as mirrors, lenses, prisms,optical fibers, gratings, apertures and other elements that mayinfluence the properties or direction of light. A light path may alsoincorporate geometric alignment.

FIG. 3A illustrates an exploded view of a flow cell 120 according to theinvention and FIG. 3B illustrates a cross-sectional view of flow cell120 as assembled. Flow cell 120 comprises a light detector 122, anoptical filter 123, a conductive window 124, a shield 126, a referenceelectrode 128, couplings 130 and 132, a cell component 134, a counterelectrode 136, a gasket 138, a working electrode 140, a cell base 142, apivot arm 144, magnet 146 and a magnet detector 147.

Light detector 122 is a sensitive light detection device, such as asemiconductor photodetector, which is tolerant of relatively hightemperatures and can operate accurately in the presence of a magneticfield. Preferably, light detector 122 is sensitive to light in the400-800 nm range, is physically small, e.g., 1″x1″x0.5 or less, andcomprises a silicon photodiode. In particular, IR-suppressing photodiodemodel #S1227-66BR, manufactured by Hamamatsu, is a preferredimplementation of light detector 122. It is further preferred that lightdetector 122 be operable at ordinary electronic device voltages, e.g.,within the approximate range of +/−12 v, and not utilize the highvoltages required by devices such as a photomultiplier tube, e.g.,greater than +/−24 volts.

Light detector 122 may optionally include an optical filter as anintegral component such as, for example, a thin film deposited on thelight-collecting surface of detector 122. In particular, Hamamatsu'sIR-suppressing photodiode model #S1227-66BR is considerably lesssensitive to light of a wavelength greater than approximately 730 nmand, accordingly, demonstrates significantly improved accuracy andprecision in detecting light emitted by ECL labels comprising Ru(bpy)₃derivatives. Accordingly, an IR-suppressing light detector 122, e.g.,one that inherently avoids the detection of infrared radiation, ispreferred. Light detector 122 produces a light measurement signal as afunction of the light incident upon it.

Optical filter 123 transmits light of certain wavelengths to lightdetector 122 while substantially preventing the transmittance of lightof other wavelengths. Preferably, optical filter 123 comprises a thinfilm of optically filtering material that is coextensive with a lightdetecting area of light detector 122. Alternatively, filter 123 maycomprise any optical component capable of passing certain wavelengths oflight to light detector 122 and preventing other wavelengths of lightfrom reaching light detector 122. As a further alternative, opticalfilter 123 may not be coextensive with light detector 122.

To maximize the operating efficiency of light detector 122, thetransmittance characteristics of filter 123 are preferably matched tothe wavelengths of the light emitted by an ECL label during an ECLassay. It is specifically preferred that filter 123 absorb light havinga longer wavelength than that of the light emitted by the ECL label.Preferred embodiments of filter 123 include one or more of: i) a shortpass filter having a transmittance of 600 nm light that is more thanfour times greater than its transmittance of 1000 nm light; ii) a shortpass filter having a transmittance of 600 nm light that is more thanfour times greater than its transmittance of 800 nm light; and iii) ashort pass filter having a transmittance of 600 nm light that is morethan four times greater than its transmittance of 700 nm light, or acombination thereof. Optionally, filter 123 may be omitted from flowcell 120. Alternatively, filter 123 may be a short pass optical filterfor passing light having a wavelength of less than 800 nm, morepreferably less than 750 nm, and most preferably less than 700 nm.

In an alternate embodiment, light detector 122 comprises an avalanchephotodiode detector or an array of light detectors, such as a CCD array,CID array, a photodiode array, and the like. By utilizing an array oflight detectors and analyzing their corresponding respective lightdetection signals, different sources of light within flow cell 120 maybe differentiated from each other.

Conductive window 124 is formed of a thin, light-transmitting,electrically-conductive material shaped to be coextensive with aperture125. Alternatively, conductive window 124 is not coextensive withaperture 125. Preferably, window 124 includes a metallic mesh comprisingcopper, brass, or the like. Alternatively, window 124 may comprise atransparent, conductive material such as a thin film of indium-tin oxidedeposited on a transparent substrate. It is further contemplated thatwindow 124 may comprise an electrically conductive or otherwiseelectrostatically shielding configuration of a solid, liquid, gel, orgas. Window 124 shields light detector 122 from electrical noise thatmight adversely affect its performance; thus window 124 is electricallyshielded. The light transmittance of window 124 should be greater than40% and preferably is greater than 70%. It is most preferred that window124 have a transmittance of greater than 85% for light emitted by an ECLlabel.

Where window 124 has been implemented as a mesh, it is preferred to sizethe apertures in the mesh relative to the type of electromagneticradiation against which the mesh is to shield. For example, mesheshaving apertures of less than 1 mm, or more preferably less than 0.7 mm,or most preferably less than 0.3 mm, have been found to effectivelyshield against the apparent capacitive coupling between light detector122 and one or more of working electrode 140 and counter electrode 136.

Shield 126 comprises a generally opaque configuration ofelectrically-conductive material, such as brass, aluminum or the like,preferably shaped like an open container. Shield 126 has an open top toaccommodate installation of light detector 122 and a bottom surfacehaving an aperture 125 adapted to accommodate conductive window 124.optionally, aperture 125 is adapted to additionally accommodate opticalfilter 123. As a further option, shield 126 may include a top surface tothereby completely surround light detector 122. Alternatively, shield126 may comprise an electrically-conductive, and preferably transparent,coating upon or within light detector 122 and, thus, window 124 and/orshield 126 may optionally be omitted.

As a further alternative, shield 126 may be omitted if light detector122 is of a type not adversely affected by capacitive interference orelectric fields. Shield 126 may have a bottom surface which bothconducts electricity and transmits light but omits any aperture, e.g.,has a continuous bottom surface. Of course, shield 126 and conductivewindow 124 may be contiguous, e.g., a brass shield having a perforatedbottom surface.

An optical epoxy, such as a multi-part epoxy, may be used to bondtogether light detector 122, filter 123, window 124, shield 126, andcell component 134 or any subset thereof. Preferably, the optical epoxyfills in all the gaps, if any, between the elements, thereby ensuring anoptional path between cell component 134 and light detector 122 whichomits solid/air and liquid/air interfaces.

Couplings 130 and 132 are conventional fluid couplings for connectingfluid-carrying tubes to cell component 134. Reference electrode 128 isan ECL reference electrode for detecting the voltage level of an assaysample. Preferably, reference electrode 128 includes a ceramic or glassfrit along with an ionic transfer medium, and engages in only a minimalfluid transaction with the assay sample. It is additionally preferredthat electrode 128 be entirely replaceable and modularly renewable. Theinvention allows for increased lifetime of the ECL cell by improveddesign of the reference electrode. In one embodiment, the volume of themedium in the reference electrode is greater than 0.3 cubic inches.Alternatively, the reference electrode may be omitted.

Cell component 134 is comprised of a rigid material and is shaped toinclude a central well 129, coupling opening 131 to accommodate coupling132, another coupling opening (not shown) to accommodate coupling 130, areference electrode opening (not shown) to accommodate referenceelectrode 128, and a counter electrode groove (not shown) to accommodatecounter electrode 136. As shown, the box-shaped central well 129 isadapted to accommodate shield 126, window 124, and, optionally, opticalfilter 123. Preferably, cell component 134 comprises a durable,transparent and chemically inert material such as plexiglass, acrylic,polymethyl methacrylate, or the like. Alternatively, component 134 maybe comprised of a non-transparent material except for at least some ofits volume between its lower surface (which includes the counterelectrode groove) and central well 129. At minimum, base 127 of centralwell 129 should provide a transparent zone (e.g., an optical pathway orwindow) between ECL chamber 139 and light detector 122 through whichlight generated in ECL chamber 139 may pass.

Counter electrode 136 comprises a conductive electrode having one ormore openings 133 therein. Opening 133 is preferably circular; but, mayinstead be oval, triangular, rectangular, diamond-shaped, trapezoidal oranother shape. Preferably, counter electrode 136 is comprised of ametal, such as nickel, stainless steel, gold or platinum. Counterelectrode 136 may comprise a mesh or a screen. Counter electrode 136 ispreferably shaped to fit a counter electrode groove in component 134 forsecure mounting. For example, counter electrode 136 may be “L”-shaped,as shown, rectangular in shape, “T”-shaped or the like. The “L”-shapeand “T”-shape are particularly advantageous in that one “arm” of theconfiguration may be positioned to extend beyond the periphery ofcomponent 142 to provide an electrical contact point for the provisionof electrical energy.

Gasket 138 comprises a conventional gasket material (e.g., siliconerubber) which is preferably pliable and elastomeric so as to mosteffectively provide fluid-tight seals to the other surfaces that defineECL chamber 139. To reduce lateral deformation of the gasket duringcompression, gasket 138 is most preferably formed from a material with adurometer number of greater than 60 Shore A points hardness. By reducinglateral deformation, it is possible to maintain a more precise controlover the lateral dimensions of ECL chamber 139 and thereby improve theprecision of ECL measurements.

In an alternate embodiment, gasket 138 comprises an elastomeric materialand another material which has a greater lateral stiffness than theelastomer. For example, gasket 138 may be formed from a layered materialcomprising a laterally stiff middle layer, such as nylon or acrylic,that resists lateral deformation and a pair of elastomeric top andbottom layers that provide fluid-tight seals. Additionally, the middlelayer could comprise a continuous solid, a network of fibers, or a mesh.In a gasket comprising a network of fibers or a mesh, the network ormesh is preferably oriented so that its longitudinal axis issubstantially perpendicular to the narrowest dimension of the gasket.

Gasket 138 includes an opening 137 that is preferably shaped to allow aneven and uniform fluid flow through ECL chamber 139, especially over thesurface of working electrode 140. Preferred shapes for opening 137include a parallelogram and a diamond. Opening 137 defines sides of ECLchamber 139.

Working electrode 140 comprises a conductive electrode, preferably madeof a metal, such as gold or platinum, formed in a planar sheet.Preferably, electrode 140 is shaped to fit within working electrodegroove 143 for secure mounting therein. For example, electrode 140 maybe “L”-shaped as shown, rectangular in shape, “T”-shaped or the like.The “L”-shape and “T”-shape are particularly advantageous in that one“arm” of the configuration may be positioned to extend beyond theperiphery of component 134 to provide an electrical contact point forthe provision of electrical energy.

Cell base 142. comprises a rigid base material having an opening 145extending therethrough, a working electrode groove 143 adapted toaccommodate working electrode 140, and a gasket groove 141 adapted toaccommodate gasket 138. Preferably, cell base 142 comprises a durableand chemically inert material, such as plexiglass, acrylic, polymethylmethacrylate, or the like. As shown, opening 145 preferably has thecross-section of a square with rounded corners but, alternatively, mayhave any shape suitable to accommodate magnet 146 and/or pivot arm 144.Optionally, opening 145 is omitted from cell base 142.

Preferably, magnet detector 147 extends into or near opening 145. Inanother embodiment, magnet detector 147 is attached to the lower surfaceof base 142 or is incorporated into base 142. Magnet detector 147preferably comprises a conventional magnetic field detector such as amagnetometer and provides an output signal indicating the presence,absence, or proximity of magnet 146 and/or pivot arm 144. In anespecially preferred embodiment, magnet detector 147 comprises one ormore Hall-effect sensors or the like. Alternatively, magnet detector 147is omitted from cell 120.

Cell component 134 and cell base 142 may be held together by aconventional retaining device incorporated into, affixed to, orassociated with one or both of component 134 and base 142. Such aretaining device may comprise screws, rivets, bolts, pins, clips,clamps, elastic fasteners, adhesives, tapes, fasteners, and the like.

Preferably, working electrode 140 is mounted in working electrode groove143 without any adhesive or permanent fastener. Instead, electrode 140fits precisely within groove 143 and is held in place by gasket 138sandwiched between cell component 134 and cell base 142. As a result,working electrode 140 is readily removed and replaced. By avoiding theuse of an adhesive or other fixing agent to secure electrode 140, theprocess for manufacturing cell 120 is simplified considerably and theuseful lifetime of cell 120 is substantially increased. The workingelectrode 140 is thus removably fitted into the cell. The cell of theinvention can have a useful lifetime greater than 10,000 assaymeasurements; preferably this lifetime exceeds 25,000 assaymeasurements; more preferably, the lifetime of the cell exceeds 50,000assay measurements; even more preferably, the lifetime exceeds 100,000measurements; most preferably the lifetime of the cell exceeds 1,000,000assay measurements.

Opening 137 in gasket 138, portions of working electrode 140 and counterelectrode 136, both defined by gasket 138, and a portion of cellcomponent 134 provide the boundaries for ECL chamber 139. Together,these elements also define a fluid path through ECL cell 120. It shouldbe appreciated that opening 137 is positioned such that the fluid pathdoes not include any seam between working electrode 140 and cell base142.

Magnet 146 is a conventional magnet device, preferably a permanentmagnet having a generally square shape, and is affixed to pivot arm 144.Alternatively, magnet 146 may comprise an electromagnet or the like.Pivot arm 144 is a generally rigid pivot arm configured to positionmagnet 146 within opening 145. At opening 145, magnet 146 may removablybe positioned to touch working electrode 140 or may be positioned nearthereto.

As shown in FIG. 3B, the registration of working electrode 140, opening137, opening 133, transparent base 127, aperture 125, conductive window124, optical filter 123 and light detector 122 is an important featureof the invention. Proper registration of these elements ensures optimaltransmittance of light from the vicinity of working electrode 140 tolight detector 122. Additionally, registration of magnet 146 and opening145 with working electrode 140 allows for the precise and efficientapplication of magnetic energy at working electrode 140. Such magneticenergy is used to attract magnetic particles from an assay sample toworking electrode 140 where electrochemiluminescence may be induced.Preferably, opening 133 itself functions as an optical element thatdefines the region of working electrode 140 and ECL chamber 139: fromwhich induced electrochemiluminescence may propagate to light detector122. Per design, counter electrode 136 may block undesired lightgenerated in certain regions of ECL chamber 139. Preferably, the sizeand shape of the counter electrode aperture 133 is designed to maximizecollection of light emitted from those regions of the working electrode140 where magnetic beads have been deposited and minimize collection oflight emitted from other regions of the working electrode 140.

Additionally, precise registration of opening 133 and magnet 146 isparticularly important to maximize the amount of luminescenceattributable to the desired reaction (vs. luminescence attributable toancillary reactions) that is incident upon light detector 122. Thestrength and shape of the magnetic field produced by magnet 146 definesthe region in which any material attracted by the magnetic field, e.g.,magnetic beads, comes to rest. Preferably, opening 133 is sized andshaped to allow light emitted by or near such materials collected bymagnet 146 in the vicinity of working electrode 140 to reach lightdetector 122 while minimizing the amount of light generated in otherregions that reaches light detector 122. Accordingly, light detector 122should be sized relative to opening 133 (or vice versa to ensure thatthe desired electrochemiluminescence is collected. Preferably theworking area of light detector 122 is slightly larger than the crosssectional area of the light cone generated at the electrode and emittedthrough aperture 133.

FIGS. 4A, 4B, 4C, and 4D illustrate detailed views of cell component134. FIG. 4A is a cross-sectional view of cell component 134 taken alongthe line 4A—4A of FIG. 4B. FIG. 4B is a top view of cell component 134.FIG. 4C is a cross-sectional view of cell component 134 taken along theline 4C—4C of FIG. 4B. FIG. 4D is a bottom view of cell component 134.

FIG. 4A illustrates a side cross-sectional view of cell component 134and particularly depicts a central well 129, coupling openings 180 and131, fluid ports 182 and 186, and a counter electrode groove 184.Central well 129 preferably has a cross-section compatible with that oflight detector 122 and shield 126 (see FIG. 3A), e.g., rectangular asshown, and has a depth of approximately 75% of the depth of component134. By embedding light detector 122 in central well 129, light detector122 is positioned in close proximity to ECL chamber 139 and workingelectrode 140. Such proximity facilitates efficient light detection. Ina preferred embodiment of assembled cell 120, the distance between lightdetector 122 and working electrode 140 is less than 2.2 mm. As shown, aportion of cell component 134 separates ECL chamber 139 from centralwall 129; in a preferred embodiment, the thickness of this material isless than 1.3 mm.

Since interfaces in an optical path between materials (e.g., aplastic/air interface), interface between phases (e.g., a liquid/solid,solid/gas, or liquid/gas) or between materials with different refractiveindices, may impede light transmission, cell 120 is designed to avoid orminimize such interfaces. In particular, the optical path between lightdetector 122 and ECL chamber 139 preferably avoids any interfaces thatincludes air, e.g., an air gap. To provide optimal optical couplingamong elements in the optical path between detector 122 and chamber 139,optical adhesives and epoxies, index matched liquids, and index matchedcompliant materials, and the like are utilized to eliminate air gaps.Such optical coupling materials are especially useful in implementing amesh as shield 124 (see FIG. 3A), since the optical coupling materialsdisplace gas existing in the interstitial spaces between elements of themesh. The use of optical coupling materials to eliminate air gaps hasimproved optical efficiency by as much as 40%. In a preferredembodiment, all cell elements and optical coupling materials forming theoptical path between detector 122 and chamber 139 have refractiveindices between 1.3 and 1.6, while refractive indices between 1.45 and1.55 are especially preferred.

The light collection efficiency of cell 120 is a function of severalfactors such as, i) the strength, shape and placement of magnet 146; ii)the size, shape and position of opening 133; iii) the transmittance ofwindow 124; iv) the distance between light detector 122 and ECL chamber139; v) the efficiency of optical coupling among materials within theoptical path; vi) the size and placement of light detector 122; vii) theproperties of optical filter 123 and viii) cell geometry, e.g., thealignment of and distance between elements that comprise the opticalpath. Light collection efficiencies greater than 40% is preferred;efficiency greater than 50% is more preferred.

Coupling opening 180 is adapted to receive coupling 130 and couplingopening 131 is adapted to receive coupling 132. Counter electrode groove184 is adapted to receive counter electrode 136. A tube in component 134connects coupling opening 180 and fluid port 182. Another tube incomponent 134 connects coupling opening 131 and fluid port 186. Fluidports 182 and 186 are positioned to allow fluid to flow from one port tothe other through the ECL chamber 139 defined by opening 137 in gasket138 (sides), working electrode 140 (bottom), counter electrode 135(top), and circular hub 188 of cell component 134 (top). Thelongitudinal ends of opening 137 align with ports 182 and 186.

FIG. 4B illustrates a top view of cell component 134 and particularlydepicts central well 129. Central well 129 is adapted to receive shield126 and conductive window 124.

FIG. 4C illustrates a side cross-sectional view of cell component 134and particularly depicts a reference electrode opening 190. Opening 190intersects the tube connecting coupling opening 180 and fluid port 182.Reference electrode opening 190 is adapted to receive referenceelectrode 128.

FIG. 4D illustrates a bottom view of cell component 134 and particularlydepicts counter electrode groove 184 and circular hub 188. The surfaceof circular hub 188 is preferably flat and flush with the bottom surfaceof cell component 134. Hub 188 is preferably integral to component 134and is adapted to fit exactly within opening 133 of counter electrode136. Hub 188, along with that portion of component 134 between hub 188and central well 129 provide an optical pathway or window through whichlight may travel.

FIG. 5 illustrates an apparatus 200 incorporating an ECL measurementmodule 226 according to an embodiment of the present invention. Module226 comprises a main interface 210, a main controller 214, a heater 216,an amplifier 218, a flow cell 120, a magnet detector 220, a magnetcontroller 222, and a temperature controller 224. Also shown are a powersource 202, a host interface 204, an input fluid source 208, and anoutlet for waste 212. Module 226 is preferably housed within alight-tight enclosure.

Main interface 210 is preferably the only interface for apparatus 210and may consist of multiple individual interfaces (e.g. connectors)suitable for multiple connections. Interface 210 preferably includesremovable connections to power source 202, host interface 204, inputsource 208, and outlet 212. Since such connections are removable, module226 may be easily replaced as a single operational module. In addition,the modular design of the apparatus 226 allows for its incorporationinto a variety of other instruments through connections to maininterface 210. Preferably, the multiple connectors of main interface 210are grouped such that the connections may be engaged or disengagedtogether in a single procedure. It is an important feature of thisinvention that the connectors can be engaged or disengaged readily, andin some embodiments, without fully interrupting the function of thedevice (e.g. “hot-swapping”). Preferably, fluid connectors incorporatedinto main interface 210 are self-sealing on disengagement and/orself-opening on engagement to prevent leakage of fluid or fluid pathobstruction.

Main controller 214 is a control device, such as microcontroller PIC16C65 by Microchip or the like, for controlling the basic operation ofmodule 226 in response to commands from an external host (not shown).Main controller 214 is coupled to main interface 210, amplifier 218,flow cell 120, magnet detector 220, magnet controller 222, andtemperature controller 224. Alternatively, main controller 214 mayinclude a waveform generator such as a voltage source, a current source,a power supply, a potentiostat, or the like. Preferably, such a waveformgenerator is controllable and may be externally controllable, e.g. by anexternal control device. Preferably, such a waveform generator may becontrolled so as to generate waveforms of any shape, including steps,ramps, ramp-and-holds, sinusoids, and/or any combination of theabovementioned waveforms. The waveform is optionally repeated multipletimes. Upon receiving commands from an external host connected to hostinterface 204 through main interface 210, main controller 214 issuesappropriate commands to, and may control the supply of power to,constituent parts of module 226. Preferably main controller 214comprises a programmable timing controller, such as an electromechanicalcontrol device and, alternatively, may comprise a microprocessor-basedcontrol system. Optionally, controller 214 comprises a storage device,such as a semiconductor memory, magnetic storage media, optical storagemedia, magneto-optical storage media, and the like.

Amplifier 218 is an amplifier with controllable gain for amplifying thelight measurement signal produced by light detector 122. Preferably,amplifier 218 has a gain of between 1 and 8000. The light measurementsignal produced by light detector 122, a part of flow cell 120, may beamplified by amplifier 218 in accordance with a control signal providedby main controller 214. Optionally, the light measurement signal or anamplified version thereof is provided to main controller 214. Amplifier218 is preferably directly connected to the output of light detector122.

Flow cell 120 is the flow cell of FIG. 3 as previously described.Electrical energy is provided to cell 120 by main controller 214. Inparticular, the electrical energy may be generated by a waveformgenerator included in main controller 214.

Magnet detector 220 detects the positioning of magnet 146 and, inparticular, whether magnet 146 is or is not proximate working electrode140. Alternatively, magnet detector 220 may simply detect thepositioning of pivot arm 144. Detector 220 provides an output signal tomain controller indicative of the position of magnet 146. Magnetdetector 220 may optionally be incorporated into flow cell 120. Magnetdetector 220 is shown in FIG. 3A as magnet detector 147.

Magnet controller 222 is a control device, responsive to operationalcontrol signals from main controller 214 for controlling the positioningof magnet 146. Preferably, magnet controller 222 is anelectro-mechanical device for positioning pivot arm 144. It is furtherpreferred that proper operation of controller 222 and arm 144 areverified by reference to an output signal of magnet detector 220.

Heater 216, coupled to temperature controller 224, is a conventionalcontrolled heating device for heating input fluid to be introduced intoflow cell 120. Temperature controller 224 is a conventional temperaturecontroller for controlling the operation of heater 216 and responding tocontrol signals from main controller 214. Controller 224 receives powerfrom power source 202 via main interface 210 and, preferably, controlsthe flow of power to heater 216. Controller 224 may include temperaturesensors to determine the temperature of input fluids or, alternatively,such sensors may be incorporated into heater 216. Optionally, heater 216and/or temperature controller 224 may be omitted.

In operation, fluid supplied from input fluid source 208 via maininterface 210 may be heated by heater 216 and provided to an input offlow cell 120, specifically coupling 132. Coupling 132 transfers theinput fluid through coupling opening 131 to fluid port 186 and into ECLchamber 139. Main controller 214 controls magnet controller 222 toposition magnet 146 in proximity to working electrode 140. Magnetdetector 220 provides a signal to main controller 214 indicative of thepositioning of magnet 146.

Main controller 214 applies electrical energy to working electrode 140and counter electrode 136 to cause the input fluid toelectrochemiluminesce. Reference electrode 128 detects a referencevoltage in the input fluid and provides a corresponding referencevoltage signal to main controller 214. Main controller 214 adjusts itsapplication of electrical energy to working electrode 140 and counterelectrode 136 as a function of the reference voltage signal.

Light detector 122 detects the induced electrochemiluminescence andsupplies a light measurement signal to amplifier 218 for amplification.Amplifier 218 provides the original or amplified signal to maincontroller 214 which routes same to main interface 210 for output to thehost interface 204 and acquisition by the host (not shown).

The input fluid is pumped through ECL chamber 139 into fluid port 182and coupling 130 via coupling opening 180. The expelled fluid travelsthrough main interface 210 to outlet 212. Throughout the process, powersource 202, connected to main interface 210, provides the power neededby module 226. Through main interface 210 and host interface 204, maincontroller 214 may be controlled by an external host to process inputsample fluids at specific temperatures, with specific patterns ofelectrical energy, and with or without the application of a magneticfield.

FIG. 6 provides a flow chart illustrating a preferred method 250 of ECLtest measurement according to an embodiment of the present invention.According to method 250, in step 254, main controller 214 controlsmagnet controller 222 to control pivot arm 144 to raise magnet 146 intoa position in close proximity to working electrode 140. Magnet detector220 detects the position of the magnet to verify its proper placement.In the next step 256, an assay sample is transported to the fluid entryport of the flow cell, e.g., fluid port 186, having already passedthrough main interface 210 and heater 216. Thereafter, in step 258, theassay sample is pumped through ECL chamber 139 and materials in theassay sample are collected by the magnetic field of magnet 146 atworking electrode 140.

A washing fluid, such as an assay buffer, is then pumped through ECLchamber 139 at a relatively high speed in step 260 to wash the materialscollected by magnet 146. Thereafter, an assay fluid, such as an assaybuffer, may be pumped through ECL chamber 139 at a relatively low speed.In step 262, main controller 214 controls light detector 122, possiblythrough amplifier 218, to detect a background level of light present inECL chamber 139.

In the subsequent step 264, main controller 214 applies electricity tothe sample collected at working electrode 140. An electric field iscreated between counter electrode 136 and working electrode 140.Preferably, the electric field is generated by stepping the potential atthe working electrode to 1.4 V (vs. Ag/AgCl) and holding such voltagefor a period of two seconds. The collected sample is thereby induced toelectrochemiluminesce and the intensity of the resulting light ismeasured by light detector 122. Detector 122 provides a lightmeasurement signal to main controller 214 via amplifier 218. Maincontroller 214 may modulate the strength of the applied electric field.

The implementation of a light detector 122 that operates accurately inthe presence of a magnet field is clearly advantageous. The magneticfield concentrates sample materials at the surface of working electrode140 and prevents their dispersion. With magnet 146 raised, ECLmeasurements may be made successfully under conditions of moderate tostrong fluid flow without loss of sample. In addition, by measuring ECLunder conditions of flow, reagents consumed by the ECL process can bereplenished during the measurement.

In step 266, main controller 214 controls magnet controller 222 to causepivot arm 144 to be retracted, lowering magnet 144 away from workingelectrode 140. Thereafter, in step 268, a cleaning and/or conditioningcycle occurs. Preferably, cleaning fluid and/or air bubbles are pumpedthrough the flow cell during the cleaning cycle.

In the apparatus of the present invention, a magnet detector, e.g., aHall-sensor, independently verifies the consistencies of the magneticfield applied to fluid within ECL chamber 139. Accordingly, magneticbeads need not be used to calibrate this apparatus. ECL labels dissolvedin solution or otherwise not affiliated with materials influenced by amagnetic field can be used as standards to measure the ability of cell120 to induce and detect electrochemiluminescence independently of themagnetic field. Since magnetic bead-based calibration standards withwell-defined characteristics are difficult and expensive to manufacturereliably and may be unstable during long-term storage, it isadvantageous that cell 120 may be calibrated without the utilization ofsuch standards. Independent verification of the magnetic field with amagnet detector and utilization of an ECL standard not based on magneticbeads facilitates diagnostic methods that distinguish between magneticfield failure and electrochemiluminescence induction/detection failures.Such diagnostic precision considerably simplifies service and repair ofan instrument.

The invention includes integrated systems for measuring analytes. Thesesystems include one or more integrated ECLM modules as described above.The system may include a sample introduction device, power supplies,controllers, and electrical mechanical and fluid connections to themodules, a case or physical support and a user interface. The sampleintroduction device, power supplies, controllers, and electricalmechanical and fluid connections to the modules, a case or physicalsupport and user interface may or may not be shared by a plurality ofECL modules. The ECL modules in these systems are designed to beintegrated with other instrumentation that generates samples benefitingfrom diagnostic testing (e.g. chemical reaction chambers, bioreactors,biomolecule synthesizers, water collection systems, lithographicprocessors) without undue effort, cost or expenditure of time.

FIG. 7 illustrates an assay system 400 with multiple ECL modules 408A-D.System 400 includes a sample 15 source 402, a reagent source 404, afluid distribution network 406, ECL modules 408A-D, waste repository410, controller 412, and power supply 414. As shown, fluid distributionnetwork 406 is coupled to each of sample source 402, reagent source 404,ECL modules 408A-D, controller 412 and power supply 414. ECL modules408A-D are each further coupled to waste repository 410, controller 412and power supply 414. All connections to ECL modules 408A-D, besidesphysical supportive connections (not shown), occur through therespective main interface 210 (FIG. 5) of each. System 400 in whole, orin part, may be enclosed within a temperature-controlled environment. Inan alternative embodiment, assay system 400 includes a single ECL module408A, thus omitting ECL modules 408A, 408B and 408C. System 400 can beconfigured to accommodate any number of ECL modules 408. In hand-held orportable versions of system 400 power supply 414 may comprise a battery,fuel cell, one or more solar panels, or the like.

Sample source 402 comprises a conventional device for providing one ormore assay samples. For example, source 402 may include one or moresample probes, pipettes, pumps, valves, tubing, containers for samples,meters, flow control devices, sample preparation devices, sampleprocessing devices and other apparatus, or a combination thereof. Suchsample processing devices may include filters, mixing chambers, reactionchambers and the like. Source 402 may also include, for example,multi-well plates, cartridges, test tubes and vacuum blood draw tubes. Acartridge may include a filtration membrane for filtering blood and mayalso contain other analytical components (e.g. ion selective electrodes,oxygen electrodes). Source 402 may comprise a system for handling and/ormoving sample containers, e.g., multi-well plate stacking devices, tubecarousels or racks, and automated sample delivery systems such asconveyer belts and robotic systems. Source 402 may includeidentification (e.g. bar codes or magnetic strips) devices to identifysamples. In addition, source 402 may comprise, e.g., a separationdevice, such as a chromatography instrument or an electrophoresisinstrument. Still further, source 402 may include a network ofanalytical devices, such as a chemical reactor, a protein sequencer, aseparation device, a bioreactor, a chemical analysis instrument, or thelike. Control of such systems may be implemented through controller 412via a connection (not shown) or by another control device (not shown).

In an alternate embodiment, source 402 is the output stream of anotheranalytical device, e.g., a device for the separation of materials, suchas an HPLC or other chromatographic systems, a chemical reactionchamber, a cell culture chamber, a device for identifying and/orsynthesizing chemicals or biological materials, such as a spectrometer,a fluorometer, a protein or nucleic acid sequencer or a synthesizer.Alternatively, source 402 may include an integrated system forprocessing samples containing nucleic acids and/or for amplifyingnucleic acids. This system may include apparatus for processes such aspolymerase chain reaction (PCR), nucleic acid sequencebasedamplification (NASBA), ligase chain reaction (LCR), strand displacementamplification (SDA), transcription mediated amplification (TMA),amplification through generation of branched chains, and the like.Source 402 may comprise the flow PCR amplification devices described inU.S. Pat. Nos. 5,716,842 and 5,270,183, hereby incorporated byreference.

Reagent source 404 comprises a conventional device for providing one ormore reagents, such as ECL coreactant, binding reagents, ECL label, asuspension of magnetic beads, and the like. For example, source 404 mayinclude one or more pumps, valves, tubing, containers for reagents,reagent identification devices (e.g. bar codes or magnetic strips),meters, flow control devices and reagent preparation devices, or acombination thereof.

Fluid distribution network 406 routes sample(s) from sample source 402and reagent(s) from reagent source 404 to one or more of ECL modules408A-D. Network 406 may comprise one or more sample probes, pipettes,pumps, valves, tubing, meters, flow control devices, sample preparationdevices, and processing devices, or a combination thereof. Suchprocessing devices may include filters, mixing chambers, reactionchambers and the like. Preferably, network 406 is controlled bycontroller 412 and powered by power supply 414. Alternatively, network406 is manually controlled.

In an alternate embodiment, sample source 402 and/or reagent source 404comprise individual removable cartridges containing sample and/orreagent. Correspondingly, fluid distribution network 406 comprises acartridge receptacle for receiving a sample source 402 cartridge and/ora reagent source 404 cartridge. The individual removable cartridges mayinclude processing devices such as filters, mixing chambers, reactionchambers and the like.

One embodiment of system 400 of the invention is a device for conductingassays in multi-well (e.g. 96-well and 384-well) plates. Sample source402 is a multi-well plate (e.g. a standard format 96 well or 384 wellplate) that may include identification (e.g. bar codes or magneticstrips). Reagent source 404 is one or more containers that may includeidentification (e.g. bar codes or magnetic strips). Fluid distributionnetwork 406 includes fluid connections to source 404, 1-12 fluid probesfor sampling fluid from multi-well plates, valves, pumps, and tubing,and devices for controlling the temperature of fluids (e.g. heaters).This embodiment includes between 1 and 12 ECL measuring modules 408 asdescribed in FIG. 5 (see descriptions of modules 408A-D below). Waste410 is a conventional device for handling waste and may comprise a fluidline to a drain, a waste bottle, or an absorbent pad. Waste 410 mayinclude reagents for neutralizing chemicals, for sterilizingbiomaterials, or for neutralizing, inactivating, or detoxifyingchemicals. or other reagents. Power supply 414 is a conventional powersupply. Controller 412 may incorporate a central processing unit, akeypad, a display screen, status indicators, data storage devices,software for instrument control and data analysis, devices that monitorthe presence and placement of the multi-well plates, devices foridentifying reagents, samples and multi-well plates (e.g. bar codereaders, magnetic strip readers, modems), printing devices, networkinterface hardware and software (e.g. a network card or modem),keyboards and a mouse.

In operation, controller 412 identifies samples and reagents through useof identification devices and ensures that multi-well-plates 402 arecorrectly positioned. Controller 412 instructs fluid distributionnetwork 406 to use fluid probes to obtain samples from multi-well plates402 and to distribute the samples to ECL measurement modules 408.Controller 412 also instructs fluid distribution network 406 todistribute reagents from reagent source 404 and to deliver thesereagents to ECL measurement modules 408. In a preferred embodiment,eight fluid probes are used to sample one column of wells in a 96-wellplate; these samples are then distributed through fluid distributionnetwork 406 to eight ECL measurement modules 408. Controller 412instructs ECL modules 408 to conduct ECL measurements; controller 412receives data from ECL modules 408, processes and analyses the data, andwhen appropriate, displays and stores the data.

ECL modules 408A, 408B, 408C, and 408D are independent ECL modules. Apreferred embodiment of such an ECL module has been described above inconnection with FIG. 5. Specifically, ECL modules 408A-D should eachinclude main interface 210, main controller 214, heater 216, amplifier218, flow cell 120, magnet detector 220, magnet controller 222, andtemperature controller 224. In an alternate embodiment, ECL modules408A-D include only main interface 210, main controller 214, flow cell120, magnet detector 220, magnet controller 222, and temperaturecontroller 224. Optionally, magnet detector 220 and/or magnet controller222 may be omitted. In another alternate embodiment, ECL modules 408A-Dinclude only main interface 210, main controller 214 and flow cell 120.

Although ECL modules 408A-D are shown coupled to controller 412 andpower supply 414 in parallel, such parallel connections may be replacedby a serial connection among ECL modules 408A-D, controller 412, andpower supply 414.

Waste repository 410 is a conventional waste receiving device or systemand may include a combination of pumps, valves, tubing, containers forwaste, meters and flow control devices.

Controller 412 is a control device for controlling the operation offluid distribution network 406 and ECL modules 408A-D. Controller 412may comprise a microcontroller or a microprocessor-based control system.Alternatively, controller 412 may include a device for storing ECL dataand may utilize data analysis software to analyze and display data fromongoing ECL measurements. optionally, controller 412 comprises a storagedevice, such as a semiconductor memory, magnetic storage media, opticalstorage media, magneto-optical storage media, and the like. Controller412 may include devices for identification of samples and reagents (e.g.bar code readers or magnetic strip readers). Additionally, controller412 may be integrated with a network or central computing system thatstores data, reconciles records or performs accounting or billingfunctions or yet other functions. Optionally, controller 412 is adaptedfor remote communication with other computer systems. It is preferredthat controller 412 communicate with other components of system 400through standard data transmission protocols such as RS-232 or I²C.Controller 412 may utilize serial or parallel communication protocols incommunicating with ECL modules 408A-D.

Controller 412 may be integrated with other instruments used in themedical environment, e.g. patient monitoring systems that include ECG,respiration monitors, temperature monitors, blood pressure monitors,blood chemistry analyzers, oxygen monitors and the like. Controller 412may be integrated with other devices in the same physical housing or maybe integrated through a networked connection.

In a further embodiment, controller 412 includes a user interfacethrough which a user may control the operation of system 400. Suchinterface may include an input device, such as a keypad or a touchscreen as well as an output device, such as a display or a printer.Through the user interface, controller 412 may display ECL measurementdata, analysis of such data, and information regarding the performanceand operational characteristics of system 400.

Power supply 414 is a conventional power supply unit. Although showndirectly connected to each of fluid distribution network 406 and ECLmodules 408A-D, such connections may be omitted if power supply 414 iscoupled to controller 412 which may itself route power to each of fluiddistribution network 406, and ECL modules 408A-D.

It is desired that ECL signals reported by different ECL modules 408A-Dto controller 412 be directly comparable to one another. Since slightvariations in the operational characteristics of each ECL module mayaffect the ability of the particular module to induce and detectelectrochemiluminescence, the invention provides apparatus andmethodology for calibrating and/or normalizing the operation of multipleECL modules. According to this procedure, each ECL module is tested witha set of reference samples to generate respective sets of measuredvalues. One of the ECL modules may be designated the reference moduleand its measured values designated as reference values. Alternatively, areference ECL module may be tested with the set of reference samples toproduce reference values. From the measured values and the referencevalues, controller 412 or an external calibration/normalization devicecalculates for each ECL module a correction transform function such thatwhen the correction transform function is applied to the measuredvalues, values approaching the reference values are produced. In thesimplest case, each ECL module is normalized so that when supplied witha certain reference sample the module will output the same referencesignal (S_(R)).

Preferably, the correction transform function is generated within an ECLmodule, or provided thereto by controller 412 or by an external device.Such correction transform function may be implemented within an ECLmodule by adjusting the amplification gain applied to the light detectorsignal (S_(D)), so that the amplified light detector signal (S_(AR))produced when the reference sample is tested equals S_(R).Alternatively, correction may be carried out by calculating a correctiontransform function F_(C)=f(S_(R),S_(AR) and applying the correctiontransform function to further amplified light detector signals (S_(A))such that the output signal (S_(O)) of the ECL module isS_(O)=F_(C)(S_(A)). Preferably, F_(C) or the parameters of thecorrection transform function is stored in a memory within theparticular ECL module and correction is implemented by themicrocontroller internal to that module. Followingcalibration/normalization, the ECL modules should be completelyinterchangeable and comparable. In an alternate method, correction isachieved by a computer or microcontroller external to the ECL module,such as controller 412. Controller 412 may store in its memory an F_(C)for each ECL module it controls.

Through individual main interfaces 210, each of ECL modules 408A-D arecoupled to other components of system 400. Accordingly, individual ECLmodules are conveniently removed and replaced.

Optionally, ECL modules 408A-D share a common light detection deviceprovided in controller 412 and are optically coupled thereto via anoptical connector such as a fiber optic line.

In operation, fluid distribution network 406, under the control ofcontroller 412, retrieves one or more samples from sample source 402and, optionally, one or more reagents from reagent source 404. Powersupply supplies necessary power to network 406, ECL modules 408A-D, andcontroller 412. The sample(s) and reagent(s) are distributed to one ormore of ECL modules 408A-D. Controller 412 controls each of ECL modules408A-D to conduct at least one ECL assay upon the sample(s), utilizingselected reagent(s). Results from the ECL assays are provided tocontroller 412. Controller 412 controls fluid distribution network 406to draw additional sample(s) and/or reagent(s) from sources 402 and 404,respectively, and provide same to particular ECL modules as the ECLassays are completed. The additional fluid displaces the assayedmaterials which are flushed to waste repository 410.

FIGS. 8A and 8B illustrate external views of certain components ofsystem 400. In FIG. 8A, an ECL module 408A is shown comprising anenclosure 448A, a pair of rails 450A, fluid connectors 452A and 456A,and electrical connector 454A. It is preferred that all of ECL modules408A-D have the same external features and elements as shown in FIG. 8A.For point of reference, it should be understood that fluid connectors452A and 456A together with electrical connector 454A comprise a maininterface 210, as discussed above.

Enclosure 448A is a rigid enclosure for containing the components of ECLmodule 408A and is preferably light-tight, thermally-insulated, andelectrically conductive to shield the components of the ECL module fromexternal environmental variations. ECL module 408A has a volume lessthan 50 cubic inches; preferably it has volume less than 25 cubicinches. A pair of rails 450A are attached to enclosure 448A formechanical engagement with complementary structures in chassis 458 ofsystem 400 (shown in FIG. 8B). Rails 450A may be integral to enclosure448A. Alternatively, rails 450A could be replaced with anothermechanical engagement device for securely connecting ECL module 408A andchassis 458.

Fluid connectors 452A and 456A provide connections for fluid input toand output from ECL module 408A. For example, fluid connector 452A mayconnect to heater 216, or directly to flow cell 120, of module 408A.Similarly, fluid connector 456A may connect to the fluid output of flowcell 120. Electrical connector 454A provides a connection for power,data, and control signals. Preferably, electrical connector 454Aincludes a printed circuit board connector. Power connections inconnector 454A may connect directly to main controller 214 andtemperature controller 224 of module 408A. Data and control signalconnections in connector 454A may connect directly to main controller214.

In FIG. 8B, a chassis 458 of system 400 is illustrated. Chassis 458, arigid enclosure for containing the components of system 400, includes anumber of module receptacles 460A-D. Optionally, chassis 458 may beinsulated and include a heater or a conventional temperature controller.Module receptacle 460A includes grooves 462A, fluid connectors 464A and468B, and electrical connector 466A. As shown, module receptacles 460A-Dhave the same features and include the same elements.

Grooves 462A are adapted for complementary engagement with rails 450A ofenclosure 448A. Grooves 462A may comprise separate structures attachedto chassis 458A. Preferably, rails 450A and grooves 462A provide afacile, secure, yet removable structural connection between ECL module408A and chassis 458. Rails 450 and grooves 462A should be arranged tominimize the potential for damage to connectors 452A, 454A, and 456A ofmodule 408A during insertion of module 408A into chassis 458 and toprevent misaligned insertion. Removable coupling of the ECL modules tochassis 458 is preferred to allow for quick and easy replacement of themodules. Of course, many conventional configurations of mechanicalengagement structures and mechanisms may be substituted for rails 450and grooves 462A. Preferably, the mechanical fluid and electricalconnections are engaged or disengaged together in one operation. It isan important feature of this invention that the connectors can beengaged or disengaged readily, and in some embodiments, without fullyinterrupting the function of the device (e.g. “hot-swapping”).

Fluid connectors 464A and 468A provide connections for fluid exchangewith system 400. Preferably, fluid connector 464A is connectable tofluid connector 456 and itself connects to waste repository 410. Fluidoutput from a flow cell 120 is thus routed to waste repository 410.Fluid connector 468A is preferably connectable to fluid connector 452Aand itself connects to fluid distribution network 402. Sample(s) and/orreagent(s) are distributed by fluid distribution network 402 viaconnectors 468A and 452A to heater 216 or flow cell 120. Electricalconnector 466A is connectable to electrical connector 454 and itselfconnects to controller 412 and/or power supply 414. It is preferred thatthe fluid and electrical connections be made simply by sliding an ECLmodule into one of module receptacles 460A-D. Preferably, fluidconnectors 452A, 456A, 464A and 468A are self-sealing on disengagementand/or selfopening on engagement to prevent leakage of fluid or fluidpath obstruction.

System 400 is adapted for integration into diagnostic devices forperforming large numbers of chemical or biochemical analyses at veryhigh speeds. A high volume of diagnostic tests can be performed byoperating a plurality of ECL modules in parallel. By carrying outmultiple ECL assays simultaneously, overall assay throughput can bedramatically increased. In one embodiment, more than 150 assaymeasurements are conducted in one hour. In a preferred embodiment, morethan 500 assay measurements are conducted in one hour. In a morepreferred embodiment, more than 750 assay measurements are conducted inone hour. In a still more preferred embodiment, more than 10,000 assaymeasurements are conducted in one hour. on a system-wide basis,coordination of the ECL modules and processing of data therefrom may beaccelerated by utilizing parallel connections to the ECL modules for thetransmission of control and data signals. However, in certainapplications serial connections of control and data signals among ECLmodules improves system performance.

Advantageously, a precise number of ECL modules may be incorporated intoa system to fit the precise needs of the application. System 400 iseasily modified by changing the number of ECL modules.

For some applications it is advantageous to have an assay system capableof performing ECL-based assays as well as assays employing otherdetection technologies, e.g., fluorescence, optical absorbance,chemiluminescence, potentiometry, amperometry, and other conventionaldiagnostic detection methods. See, e.g., Tietz Textbook of ClinicalChemistry, 2nd Edition, C. Burtis and E. Ashwood, Eds., W. B. SaundersCo. Philadelphia, 1994 and The Immunoassay Handbook, D. Wild, Ed.,Stackton Press: New York, 1994, both hereby incorporated by reference.The modular nature of the ECL measurement module allows for thestraightforward development of such hybrid systems. FIG. 9A illustratesa hybrid assay system 500 for conducting an ECL assay and/or anotherassay upon a single sample. System 500 comprises sample source 402,reagent source 404, a fluid distribution network 502, an ECL module 504,an assay device 506, waste repository 410, and a controller 508. Adetailed description of these subsystems has already been presentedabove. Sample source 402 and reagent source 404 are coupled to fluiddistribution network 502 and provide fluids thereto.

Fluid distribution network 502, routes sample(s) from sample source 402and reagent(s) from reagent source 404 to ECL module 504. Network 502may comprise one or more sample probes, pipettes, pumps, valves, tubing,meters, filters, processing devices, mixing chambers or reactionchambers and other apparatus as described above, or a combinationthereof. Preferably, network 502 is controlled by controller 508, oralternatively, network 502 is manually controlled. In an alternateembodiment, sample source 402 and/or reagent source 404 compriseindividual removable cartridges containing sample and/or reagent.Correspondingly, fluid distribution network 502 comprises a cartridgereceptacle for receiving a sample source 402 cartridge and/or a reagentsource 404 cartridge.

ECL module 504 is an independent ECL module as described above inconnection with FIG. 5. ECL module 504 is controlled by controller 508and may be controlled to pass an input fluid to its output withoutconducting an assay. ECL module 504 contains the several elementsdescribed above in connection with FIG. 7.

Assay device 506 is a conventional assay device, such as an assay deviceutilizing fluorescence, optical properties, chemiluminescence,potentiometry, amperometry or other phenomena. Assay device 506 may alsoinclude e.g., a separation device, such as a chromatography instrumentor an electrophoresis instrument or an analytical device e.g. a gaschromatograph or a mass spectrometer. Assay device 506 receives fluidoutput from ECL module 504. Assay device 506 is controlled by controller508 and may be controlled to pass an input fluid to its output withoutconducting an assay. Fluid output be assay device 506 is routed to wastereceptacle 410.

Controller 508 is a control device for controlling the operation offluid distribution network 502, ECL module 504, and assay device 506.Controller 508 may comprise a microcontroller, a microprocessor-basedcontrol system or other controller and may include a device for storingECL data and may utilize data analysis software to analyze and displaydata from ongoing ECL measurements. Controller 508 may be integratedwith a network or central computing system and may be adapted for remotecommunication with other computer systems as described above withrespect to controller 412 in connection with FIG. 7.

In a further embodiment, controller 508 includes a user interfacethrough which a user may control the operation of system 500. Suchinterface may include input and output devices as described above.Through the user interface, controller 508 may display ECL measurementdata, analysis of such data, and information regarding the performanceand operational characteristics of system 500.

In operation, fluid distribution network 502, under the control ofcontroller 508, retrieves one or more samples from sample source 402and, optionally, one or more reagents from reagent source 404. Thesample(s) and reagent(s) are distributed to ECL module 504 as describedabove with respect to fluid distribution network 406 in connection withFIG. 7. Controller 508 may control ECL module 504 to conduct one or moreECL assay upon the sample(s), utilizing selected reagent(s), or to notconduct an assay at all. Results from the ECL assay are provided tocontroller 508. Controller 508 controls fluid distribution network 502to draw additional sample(s) and/or reagent(s) from sources 402 and 404,respectively, and provide same to ECL module 504. The additional fluidcauses the materials within the module to flow to assay device 506.

Controller 508 may control assay device 506 to conduct one or moreassays upon the sample(s), utilizing selected reagent(s), or to notconduct an assay at all. Results from the assay are provided tocontroller 508. Additional fluid provided by network 502 may flushmaterials within device 506 to waste repository 410. Thus, one or bothof module 504 and device 506 may be used to conduct measurements on agiven sample.

In an alternate embodiment, system 500 includes multiple ECL modules 504and/or multiple assay devices 506 connected in series and controlled bycontroller 508. FIG. 9B illustrates a hybrid assay system 550 forconducting an ECL assay and/or another assay upon a single sample.System 550 comprises sample source 402, reagent source 404, a fluiddistribution network 552, ECL module 504, assay device 506, wasterepository 410, a system controller 556, a device 558 and a controller554. A detailed description of these subsystems appears above. Samplesource 402 and reagent source 404 are coupled to fluid distributionnetwork 552 and provide fluids thereto.

Fluid distribution network 552 includes subsystems described above. Itroutes sample(s) from sample source 402 and reagent(s) from reagentsource 404 to ECL module 504 and to assay device 506. Network 552 iscontrolled by controller 554 or manually. In an alternate embodiment,sample source 402 and/or reagent source 404 comprise individualremovable cartridges containing sample and/or reagent. Correspondingly,fluid distribution network 552 comprises a cartridge receptacle forreceiving a sample source 402 cartridge and/or a reagent source 404cartridge. A fluid connection between ECL module 504 and assay device506 may optionally be omitted.

Controller 554 is a control device for controlling the operation offluid distribution network 552, ECL module 504, and assay device 506.Operation of controller 554 may be controlled by system controller 556.Controller 554 is as described above with respect to controller 412 inconnection with FIG. 7. In a further embodiment, controller 554 includesa user interface through which a user may control the operation ofsystem 550. Such interface may include input and output devices asdiscussed above.

System controller 556 comprises a system control device, coupled tocontroller 554 and to device 558. Controller 556 is preferably amicrocontroller or a microprocessor-based computer such as a personalcomputer, a network server or the like. Controller 556 may be integratedwith a network or central computing system that stores data, reconcilesrecords or performs accounting or billing functions or yet otherfunctions. Optionally, controller 556 is adapted for remotecommunication with other computer systems. It is preferred thatcontroller 556 utilize standard data transmission protocols such asRS-232 or I²C to communicate with other components of system 550.Controller 556 may utilize serial or parallel communication protocols.System controller 556 controls the operation of system 550 throughcontroller 554 as well as the operation of device 558. Controller 556may collect and process data from ECL module 504, assay device 506 anddevice 558. It may also include an instrument interface and controloutput to display devices (not shown). Optionally, system controller 556may be omitted.

Device 558 provides additional information, data and control signalsthat may be additional to, incorporated into, or used to generate orprocess information, data and control signals provided by devices 504and 506 and controllers 554 and 556. Device 558 comprises one or moreconventional devices including patient monitoring devices, analyticalequipment, instrument controlling devices, and the like. Patientmonitoring devices may include cardiac monitors and performanceindicators (e.g. EKG), respiration monitors, blood pressure monitors,temperature monitors, blood gas monitors (for example an oxygenelectrode, blood chemistry monitors (e.g. devices that use ion selectiveelectrodes), drug/anesthesia monitors, imaging equipment and otherconventional devices. Analytical equipment includes equipment forchemical and biochemical analysis. Instrument controlling devicesinclude remote controls, data input devices, data. output devices, andcommunication devices. Optionally, device 558 may be omitted.

In operation, fluid distribution network 552, under the control ofcontroller 554, retrieves one or more samples from sample source 402and, optionally, one or more reagents from reagent source 404.Controller 554 may be controlled by system controller 556 to commencesuch operation. The sample(s) and reagent(s) are distributed to eitheror both of ECL module 504 and assay device 506. Controller 554 maycontrol ECL module 504 to conduct one or more ECL assays upon thesample(s), utilizing selected reagent(s), or to not conduct an assay atall. Controller 554 may control assay device 506 to conduct one or moreassays upon the sample(s), utilizing selected reagent(s), or to notconduct an assay at all. Results from the ECL assay and the other assayare provided to controller 554 and, optionally, to system controller556.

System controller 556 provides overall system coordination bycontrolling the operation of controller 554 and device 558. Data andother signals from devices 504, 506 and 558 and controller 554 arereceived by controller 556. Controller 556 processes, stores and/ordisplays these data and signals. Such processing may include datareduction and analysis and organization of the data using expert systemalgorithms to produce other information. Controller 556 may also senddata and signals to devices 504, 506 and 558 and to controller 554.Controller 556 may also send data and signals to output devices (e.g.printers, monitors, etc.) (not shown).

Controller 554 controls fluid distribution network 552 to drawadditional sample(s) and/or reagent(s) from sources 402 and 404,respectively, and provide same to either or both of ECL module 504 andassay device 506. The additional fluid causes the materials withinmodule 504 and/or assay device 506 to flow to waste repository 410.Thus, one or both of module 504 and device 506 may be used to conductmeasurements on a given sample. In an alternate embodiment, system 550includes multiple ECL modules 504 and/or multiple assay devices 506connected in parallel and controlled by controller 554.

In another operation, fluid distribution network 552, under the controlof controller 554, retrieves one or more samples from sample source 402and, optionally, one or more reagents from reagent source 404.Controller 554 may be controlled by system controller 556 to commencesuch operation. The sample(s) and reagent(s) are distributed to ECLmodule 504. Controller 554 controls ECL module 504 to conduct one ormore ECL assays upon the sample(s), utilizing selected reagent(s), or tonot conduct an assay at all. The sample(s) and reagent(s) are thendistributed from ECL module 504 to assay device 506. Controller 554controls assay device 506 to conduct one or more assays upon thesample(s), utilizing selected reagent(s), or to not conduct an assay atall. Results from the ECL assay and the other assay are provided tocontroller 554 and, optionally, to system controller 556. Optionally,the fluid path between fluid distribution network 552 and assay device506 is omitted. Optionally, the fluid path between ECL module 504 andwaste 410 may be omitted.

Controller 554 controls fluid distribution network 552 to drawadditional sample(s) and/or reagent(s) from sources 402 and 404,respectively, and provide same to ECL module 504 and therethrough toassay device 506 (via ECL module 504). The additional fluid causes thematerials within module 504 and/or assay device 506 to flow to wasterepository 410. Thus, one or both of module 504 and device 506 may beused to conduct measurements on a given sample. In an alternateembodiment, system 550 includes multiple ECL modules 504 and/or multipleassay devices 506 connected in series and controlled by controller 554.

In another operation, fluid distribution network 552, under the controlof controller 554, retrieves one or more samples from sample source 402and, optionally, one or more reagents from reagent source 404.Controller 554 may be controlled by system controller 556 to commencesuch operation. The sample(s) and reagent(s) are distributed to assaydevice 506. Controller 554 controls assay device 506 to conduct one ormore assays upon the sample(s), utilizing selected reagent(s), or to notconduct an assay at all. The sample(s) and reagent(s) are thendistributed from assay device 506 to ECL module 504. Controller 554controls ECL module 504 to conduct one or more ECL assays upon thesample(s), utilizing selected reagent(s), or to not conduct an assay atall. Results from the ECL assay and other assay are provided tocontroller 554 and, optionally, to system controller 556. Optionally,the fluid path between fluid distribution network 552 and ECL module 504may be omitted. Optionally, the fluid path between the assay device 506and waste 410 can be omitted.

Controller 554 controls fluid distribution network 552 to drawadditional sample(s) and/or reagent(s) from sources 402 and 404,respectively, and provide same to assay device 506 and therethrough toECL module 504. The additional fluid causes the materials within module504 and/or assay device 506 to flow to waste repository 410. Thus, oneor both of module 504 and device 506 may be used to conduct measurementson a given sample. In an alternate embodiment, system 550 includesmultiple ECL modules 504 and/or multiple assay devices 506 connected inseries and controlled by controller 554.

FIGS. 10A, 10B, 10C and 10D illustrate external views of certaincomponents of system 550. FIG. 10A depicts an external view ofintegrated assay subsystem 560 comprising an enclosure 1448A, a pair ofrails 1450A, and electrical connector 1454A. Assay system 560 issecurely mounted within enclosure 1448A. Enclosure 1448A is an enclosurefor the components of assay subsystem 560 and is preferably light-tight,thermally-insulated, and electrically conductive to shield thecomponents of the subsystem from external environmental variations. Apair of rails 1450A are attached to enclosure 1448A for mechanicalengagement with complementary structures in chassis 1458, e.g., grooves462A (shown in FIG. 10D). Rails 1450A may be integral to enclosure1448A. Alternatively, rails 1450A could be replaced with anothermechanical engagement device for securely connecting enclosure 1448A tochassis 1458. Electrical connector 1454A provides a connection forpower, data, and control signals to or from controller 554.

FIG. 10B depicts an external view of device 558 comprising an enclosure1448B, a pair of rails 1450B, and electrical connector 1454B. Device 558is securely mounted within enclosure 1448B. Enclosure 1448B is anenclosure for the components of device 558. A pair of rails 1450B areattached to enclosure 1448B for mechanical engagement with complementarystructures in chassis 1458, e.g., grooves 462A (shown in FIG. 10D).Rails 1450B may be integral to enclosure 1448B. Alternatively, rails1450B could be replaced with another mechanical engagement device forsecurely connecting enclosure 1448B to chassis 1458. Electricalconnector 1454B provides a connection for power, data, and controlsignals to or from device 558.

FIG. 10C depicts an external view of system controller 556 comprising anenclosure 1448C, a pair of rails 1450C, and electrical connector 1454C.Controller 556 is securely mounted within enclosure 1448C. Enclosure1448C is an enclosure for the components of controller 556. A pair ofrails 1450C are attached to enclosure 1448C for mechanical engagementwith complementary structures in chassis 1458, e.g., grooves 462A (shownin FIG. 10D). Rails 1450C may be integral to enclosure 1448C.Alternatively, rails 1450C could be replaced with another mechanicalengagement device for securely connecting enclosure 1448C and chassis1458. Electrical connector 1454C provides a connection for power, data,and control signals to or from controller 556.

In FIG. 10D, a chassis 1458 is illustrated. Chassis 1458, a rigidenclosure for containing one or more of subsystem 560, device 558 and/orsystem controller 556, includes a number of system receptacles 1460A-D.Optionally, chassis 1458 may be insulated and include a heater or aconventional temperature controller. System receptacles 1460A-D includesgrooves 462A-D and electrical connectors 466A-D, respectively. As shown,system receptacles 1460A-D have the same features and include the sameelements. Thus, it is preferred that each of enclosures 1448A-C becomplementary to each of system receptacles 1460A-D.

Grooves 462A-D are adapted for complementary engagement with rails1450A-C of enclosures 1448A-C. Grooves 462A-C may comprise separatestructures attached to chassis 1458. Preferably, rails 1450A-C andgrooves 462A-D provide facile, secure, yet removable structuralconnections between chassis 1458 and enclosures 1448A, 1448B, and 1448C.

The Rails and grooves should be arranged to minimize the potential fordamage to the electrical connector of the enclosure during its insertioninto the electrical connector of the chassis and to prevent misalignedinsertion. Removable coupling of the enclosure(s) with chassis 1458 ispreferred to allow for quick and easy replacement of the enclosedsystems and devices. Of course, many conventional configurations ofmechanical engagement structures and mechanisms may be substituted forthe rails and grooves. Preferably, the mechanical and electricalconnections are engaged or disengaged together in one operation. It isan important feature of this invention that the connectors can beengaged or disengaged readily, and in some embodiments, without fullyinterrupting the function of the device (e.g., “hot-swapping”).

Electrical connectors 466A-D are adopted for connection to any ofelectrical connectors 1454A-C. Electrical connectors 466A-D may beconnected to each other in series. Optionally, connectors 466A-D mayalso be connected to a power supply (not shown). Alternatively, theelectrical connector to which system controller 556 is (or will be)connected may itself be connected to the connectors in series, parallel,or a combination thereof. It is preferred that the electricalconnections be made simply by sliding an enclosure 1448A-C into one ofsystem receptacles 1460A-D. The arrangement of mechanical and electricalconnections between receptacles 1460A-D and subsystem 560, device 558and system controller 556 are similar to those described above inconnection with subsystem 560 and receptacle 1460A.

In one embodiment, the receptacles 460B-D are identical to receptacle460A. In another embodiment, any of receptacles 460A-D can be engaged toany of system 560, device 558, and controller 556. In anotherembodiment, each of receptacles 460A-D are designed specifically for oneof system 560, device 558, and controller 556 and, optionally, grooves462A-D differ to accommodate differences among rails 1450A, 1450B, and1450C and to prevent insertion of a module into a receptacle notintended for that module. Although FIG. 10D shows four receptacles1460A-D, chassis 1458 may be expanded or contracted to include anynumber of receptacles.

According to another embodiment of the invention, a single module thatcan conduct both ECL measurements and non-ECL measurements is provided.Such a multiple measurement ECL module is capable of making ECLmeasurements and one or more of the following type of measurements:optical absorbance, fluorescence, phosphorescence and light scattering.FIG. 11 illustrates an exploded view of a flow cell 600 capable of bothECL measurements and non-ECL measurements. Flow cell 600 comprises lightdetectors 122 and 612, optical filter 123, conductive window 124, shield126, reference electrode 128, couplings 130 and 132, cell components 134and 604, counter electrode 136, gaskets 138 and 614, light generator602, working electrode 140, cell base 142, pivot arm 144, magnet 146 andmagnet detector 147. Detailed descriptions of light detector 122,optical filter 123, conductive window 124, shield 126, referenceelectrode 128, couplings 130 and 132, cell component 134, counterelectrode 136, gasket 138, light generator 602, working electrode 140,cell base 142, pivot arm 144, magnet 146 and magnet detector 147 havebeen provided hereinabove with reference. to FIG. 3A.

Light detector 612 is a conventional light detection device, such as aCCD or photodiode array, for detecting light in ECL chamber 139.Detector 612 may have limited sensitivity to certain wavelengths oflight or include optical devices, such as a filter, to allow detectionof particular types of light. Preferably, detector 612 is configured toallow the measurement of individual spectral components of light.Optionally, light detector 612 is omitted.

Light generator 602 is a conventional light source for conductingassays. Generator 602 may be utilized to generate any usual lightfrequency for fluorescence or phosphorescence measurements, measurementof optical properties such as absorption and light scattering, and thelike. Generator 602 may include a wavelength selection device, such as adiffraction grating or filter, to select light with certain spectralproperties. As shown, it is preferred that light generator 602 and lightdetector 612 include a fiber optic extension for carrying light directlyfrom ECL chamber 139. Gasket 614 is identical in all respects to gasket138.

Cell component 604 comprises the same material as cell component 134. Asshown, component 604 includes an opening 610 which has thecross-sectional shape as that of gasket opening 137. Opening 610 definesa portion of the sides of ECL chamber 139. Two bore holes 606 and 608extend from opposite sides of component 604 towards but not intersectingwith opening 610. Bore holes 606 and 608 are adapted to receive thefiber optic extensions of light generator 602 and light detector 612. Inan alternate embodiment, bore holes 606 and 608 do intersect opening610. Also, cell component 604 includes two gasket grooves 141, one onthe top surface and one on the bottom surface (not shown) of cellcomponent 604.

Flow cell 600 operates similarly to flow cell 120, previously described,but with the added capability of conducting optical absorbance,fluorescence, phosphorescence and light scattering measurements and likemeasurements of optical properties. Light generator 602 is controlled bya controller (not shown) to emit light through its optics extension toECL chamber 139. Light detector 612 detects either the transmitted,scattered or emitted light or other light generated within ECL chamber139. The generated light may be induced by the emitted light or be theresult of ECL or both.

In an alternate embodiment, bore holes 606 and 608 are arranged at anangle to one another such that light emitted from light generator 602does not substantially impinge upon light detector 612. With such anarrangement, light scattering measurements, luminescence measurements,and the like may be conducted. Optionally, light detector 122. isutilized for the detecting light for optical absorbance, fluorescence,phosphorescence and light scattering measurements and like measurementsof optical properties.

The apparatus and methods of the invention as described above may begenerally applied to conducting ECL assays and assays using otherdetection techniques. Assays that may be conducted include thosedescribed in the following documents, hereby incorporated by reference:U.S. Pat. Nos. 5,221,605; 5,527,710; 5,591,581; 5,597,910; 5,610,075;5,641,623; 5,643,713; Published PCT: Application No. WO 9628538; TietzTextbook of Clinical Chemistry. 2nd Edition, C. Burtis and E. Ashwood,Eds., W. B. Saunders Co. Philadelphia, 1994 and The ImmunoassayHandbook, D. Wild, Ed., Stackton Press: New York, 1994. For example, theforegoing apparatus and methodology may implement binding assays incompetitive and noncompetitive formats, e.g., receptor-ligand bindingassays, nucleic acid hybridization assays, immunoassays, and the like aswell as assays of enzymes or enzyme substrates by measurement ofcatalytic activity, assays of gasses and electrolytes (e.g., bloodgasses and electrolytes), and clinical chemistry assays.

Although illustrative embodiments of the present invention andmodifications thereof have been described in detail herein, it is to beunderstood that this invention is not limited to these preciseembodiments and modifications, and that other modifications andvariations may be effected therein by one skilled in the art withoutdeparting from the scope and spirit of the invention as defined by theappended claims.

What is claimed is:
 1. An apparatus for the conduct ofelectrochemiluminescence measurements comprising: a cell having at leastone cell wall which includes a transparent portion adjacent to an ECLchamber defined within said cell; a working electrode abutting said ECLchamber and in optical registration with said transparent portion; acounter electrode abutting said ECL chamber; a photodiode in opticalregistration with said transparent portion; an optical filter adjacentto and in optical registration with said transparent portion; andwherein said optical filter is a shortpass optical filter for passinglight having a wavelength of less than 750 nm.
 2. The apparatusaccording to claim 1 wherein said shortpass optical filter comprises anIR-suppressing filter.
 3. The apparatus according to claim 1 whereinsaid shortpass optical filter comprises a filter having a firsttransmittance of 600 nm light and a second transmittance of 1000 nmlight, wherein said first transmittance is at least four times greaterthan said second transmittance.
 4. An apparatus for the conduct ofelectrochemiluminescence measurements comprising: a cell having at leastone cell wall which includes a transparent portion adjacent to an ECLchamber defined within said cell; a working electrode abutting said ECLchamber and in optical registration with said transparent portion; and acounter electrode abutting said ECL chamber and having an aperture inoptical registration with said transparent portion, said counterelectrode defining the entire perimeter of said aperture.
 5. Theapparatus according to claim 4 further comprising a photodetector.
 6. Anapparatus for the conduct of electrochemiluminescence measurementscomprising: a cell having at least one cell wall which includes atransparent portion adjacent to an ECL chamber defined within said cell;a working electrode having a planar electrode surface abutting said ECLchamber and in optical registration with said transparent portion ofsaid cell wall, said working electrode being positioned within the cellsuch that no seam between an edge of said working electrode and saidcell is in contact with said ECL chamber; and a counter electrodeabutting said ECL chamber.
 7. The apparatus according to claim 6 furthercomprising a photodetector.
 8. The apparatus according to claim 6further comprising a gasket interposed between said working electrodeand said counter electrode, said gasket abutting said ECL chamber, saidworking electrode, and said counter electrode.
 9. An apparatus for theconduct of electrochemiluminescence measurements comprising: a cellhaving at least one cell wall which includes a transparent portionadjacent to an ECL chamber defined within said cell; a working electrodeabutting said ECL chamber and in optical registration with saidtransparent portion; a counter electrode abutting said ECL chamber; aphotodiode adjacent to and in optical registration with said transparentportion; and a magnetic field generating device operable to apply amagnetic field at said working electrode; wherein said magnetic fieldgenerating device applies said magnetic field whileelectrochemiluminescence is induced in an assay fluid in said ECLchamber and detected by said photodiode.
 10. The apparatus according toclaim 9 wherein said magnetic field generating device applies saidmagnetic field while electrochemiluminescence is induced in an assayfluid flowing through said ECL chamber.
 11. An apparatus for the conductof electrochemiluminescence measurements comprising: a cell having atleast one cell wall which includes a transparent portion adjacent to anECL chamber defined within said cell; a working electrode abutting saidECL chamber and in optical registration with said transparent portion; acounter electrode abutting said ECL chamber; and an infrared-suppressingphotodiode adjacent to and in optical registration with said transparentportion.
 12. An apparatus for the conduct of electrochemiluminescencemeasurements comprising: a cell having at least one cell wall whichincludes a transparent portion adjacent to an ECL chamber defined withinsaid cell; a working electrode abutting said ECL chamber and in opticalregistration with said transparent portion; a counter electrode abuttingsaid ECL chamber and having an aperture in optical registration withsaid transparent portion, said counter electrode defining the entireperimeter of said aperture; a photodetector adjacent to and in opticalregistration with said transparent portion; and a magnetic fieldgenerating device in registration with said aperture, operable to applya magnetic field to said working electrode.
 13. The apparatus accordingto claim 12 wherein said photodetector comprises a photodiode.
 14. Anapparatus for the conduct of electrochemiluminescence measurementscomprising: a cell having at least one cell wall which includes atransparent portion adjacent to an ECL chamber defined within said cell;a working electrode abutting said ECL chamber and in opticalregistration with said transparent portion; a counter electrode abuttingsaid ECL chamber; a photodiode adjacent to and in optical registrationwith said transparent portion; a magnetic field generating deviceoperable to apply a magnetic field to said working electrode; and amagnetic field detector in registration with said magnetic fieldgenerating device.
 15. The apparatus according to claim 14 wherein saidmagnetic field generating device further comprises an actuator operableto move said magnetic field generating device so as to selectably applysaid magnetic field to said working electrode; and wherein said magneticfield detector determines a position of said movable magnet device bydetecting said magnetic field.
 16. The apparatus according to claim 14,wherein said magnetic field generating device applies said magneticfield while electrochemiluminescence is induced in an assay fluid insaid ECL chamber and detected by said photodiode.
 17. An apparatus forthe conduct of electrochemiluminescence measurements comprising: a cellhaving at least one cell wall which includes a transparent portionadjacent to an ECL chamber defined within said cell; a working electrodeabutting said ECL chamber and in optical registration with saidtransparent portion; a counter electrode abutting said ECL chamber; aphotodiode, adjacent to and in optical registration with saidtransparent portion, for detecting electrochemiluminescence induced inan assay fluid in said ECL chamber and for producing an ECL signalrepresentative of an intensity of said electrochemiluminescence; astorage device, coupled to said photodiode, in which a calibrationsignal representative of a calibration electrochemiluminescence may bestored; and a processor coupled to said photodiode and to said storagedevice operable to calculate a corrected signal as a function of saidECL signal and said calibration signal.
 18. A cell for the conduct ofelectrochemiluminescence measurements comprising: a first base having afirst interior surface; a planar working electrode positioned on saidfirst interior surface; a second base having a second interior surfaceand having a transparent portion therein to allow light to passtherethrough; a planar counter electrode positioned on said secondinterior surface, said counter electrode having at least one openingtherein to allow said light to pass therethrough in registration withsaid working electrode and said transparent portion of said second base,said counter electrode defining the entire perimeter of said at leastone opening; a gasket positioned between said working electrode and saidcounter electrode to define therebetween a cell volume, said volumecommunicating with the opening in said counter electrode; and aretaining device, coupled to the bases; wherein the interior surfaces ofthe bases are in opposing relationship to form said cell; and whereinsaid second base includes a conduit through which fluid may beintroduced into and removed from said cell volume.
 19. A cell for theconduct of electrochemiluminescence including cell structural elements,a working electrode and a counter electrode, at least one of saidstructural elements having a transparent portion therein, wherein saidworking electrode is mounted on an interior surface of a said structuralelement, at least a portion of said working electrode and thetransparent portion of said at least one structural element defining, atleast in part, a chamber for the conduct of electrochemiluminescence,the entirety of a wall of said chamber consisting of said workingelectrode, and said portion of said working electrode and thetransparent portion of said structural element being optically inregistration with one another.
 20. An apparatus for the conduct of assaymeasurements comprising: a cell having at least one cell wall whichincludes a transparent portion adjacent to an ECL chamber defined withinsaid cell; a working electrode abutting said ECL chamber and in opticalregistration with said transparent portion; a counter electrode abuttingsaid ECL chamber; a first light detector, optically coupled to said ECLchamber and in optical registration with said transparent portion, fordetecting electrochemiluminescence induced within said ECL chamber; anda light source, optically coupled to said ECL chamber, adapted forproviding light to said ECL chamber and for conducting luminescence,fluorescence, phosphorescence, optical absorbance, or light scatteringmeasurements.
 21. The apparatus according to claim 20 further comprisinga second light detector optically coupled to said ECL chamber andoperable to detect light from said light source.
 22. The apparatusaccording to claim 20 further comprising a second light detectoroptically coupled to said ECL chamber and operable to detect aluminescence generated within said cell.
 23. The apparatus according toclaim 20 further comprising a wavelength selection device, coupled tosaid light source, for selecting the wavelength of light provided tosaid ECL chamber.
 24. A modular ECL assay subsystem adapted for beingreadily connected to and readily disconnected from a power supply, acontroller, and a fluid exchange system common to a plurality of saidmodular ECL subsystems, said subsystem comprising: a cell having atleast one cell wall which includes a transparent portion adjacent to anECL chamber defined within said cell; a working electrode abutting saidECL chamber and in optical registration with said transparent portion; acounter electrode abutting said ECL chamber; a light detector, opticallycoupled to said ECL chamber, for detecting electrochemiluminescenceinduced within said ECL chamber; a waveform generator coupled to atleast one of said working electrode and said counter electrode andoperable to generate an electric signal; a subsystem controller coupledto said waveform generator and operable to control an operation of saidwaveform generator; and an interface to said cell, coupled to thesubsystem controller and removably coupled to said power supply, saidcontroller, and said fluid exchange system, said controller beingoperable to control said subsystem controller, said power supply beingoperable to supply electrical power to said subsystem controller, andsaid fluid exchange system being operable to provide an assay fluid tosaid cell and to receive a waste fluid from said cell.
 25. An apparatusfor the conduct of electrochemiluminescence measurements comprising: acell having at least one cell wall which includes a transparent portionadjacent to an ECL chamber defined within said cell; a working electrodeabutting said ECL chamber and in optical registration with saidtransparent portion; a counter electrode abutting said ECL chamber; anelectrically-shielded window adjacent to and in optical registrationwith said transparent portion; and a photodetector in opticalregistration with said electrically-shielded window, said transparentportion and said working electrode; wherein said photodetector is aphotodiode.
 26. The apparatus according to claim 25, wherein saidelectrically-shielded window comprises a metallic mesh.
 27. Theapparatus according to claim 26, wherein said metallic mesh includesbrass.
 28. The apparatus according to claim 26, wherein said metallicmesh includes aluminum.
 29. The apparatus according to claim 25, whereinsaid electrically-shielded window comprises a transparent conductivematerial deposited on a transparent substrate.
 30. The apparatusaccording to claim 29, wherein said transparent conductive material is afilm of indium tin oxide.